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Applied Surface Science (v.253, #4)

Study of TiN and ZrN thin films grown by cathodic arc technique by D.F. Arias; Y.C. Arango; A. Devia (pp. 1683-1690).

Thin films of TiN and ZrN were grown on stainless steel 316 substrate using the pulsed cathodic arc technique with different number of discharges (one to five discharges). The coatings were characterized in terms of crystalline structure, microstructure, elementary chemical composition and stoichiometric by X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy for chemical analyses (XPS), respectively. The XRD results show that for TiN as for ZrN, the preferential direction occurs in the plane (200), and this result stays when increasing the number of discharges. The grain size is increased with the increase of the number of discharges for both nitrides, the roughness for the TiN film is greater than for the ZrN film; these results were determined by AFM. XPS analysis determined that there is a higher nitrogen presence in the ZrN film than in the TiN film.

Keywords: TiN; ZrN; Cathodic Arc

Surface phenomena related to mirror degradation in extreme ultraviolet (EUV) lithography by Theodore E. Madey; Nadir S. Faradzhev; Boris V. Yakshinskiy; N.V. Edwards (pp. 1691-1708).

One of the most promising methods for next generation device manufacturing is extreme ultraviolet (EUV) lithography, which uses 13.5nm wavelength radiation generated from freestanding plasma-based sources. The short wavelength of the incident illumination allows for a considerable decrease in printed feature size, but also creates a range of technological challenges not present for traditional optical lithography. Contamination and oxidation form on multilayer reflecting optics surfaces that not only reduce system throughput because of the associated reduction in EUV reflectivity, but also introduce wavefront aberrations that compromise the ability to print uniform features. Capping layers of ruthenium, films ∼2nm thick, are found to extend the lifetime of Mo/Si multilayer mirrors used in EUV lithography applications. However, reflectivities of even the Ru-coated mirrors degrade in time during exposure to EUV radiation. Ruthenium surfaces are chemically reactive and are very effective as heterogeneous catalysts. In the present paper we summarize the thermal and radiation-induced surface chemistry of bare Ru exposed to gases; the emphasis is on H₂O vapor, a dominant background gas in vacuum processing chambers. Our goal is to provide insights into the fundamental physical processes that affect the reflectivity of Ru-coated Mo/Si multilayer mirrors exposed to EUV radiation. Our ultimate goal is to identify and recommend practices or antidotes that may extend mirror lifetimes.

Keywords: PACS; 82.65.+r; 68.43.−h; 79.20.LaExtreme ultraviolet lithography; EUV optics contamination; EUV optics lifetime; Ruthenium; Ru(0; 0; 0; 1); Ru; (; 1; 0; 1; ¯; 0; ); Water; Oxygen; Electron stimulated desorption; Photon stimulated desorption

Oxygen adsorption on the surface of In₂O₃ and β-(Ga_0.8In_0.2)₂O₃ mixed oxides porous structure by L.I. Ivankiv; I.V. Ketsman; V.P. Savchyn; O.A. Balitskii (pp. 1709-1712).

The paper is devoted to the oxygen sensing properties of In_1.2Ga_0.8Se₃ own oxide. The results are compared with theoretical adsorption kinetics. Temperature and time dependences of adsorption mechanisms are discussed.

Keywords: PACS; 82.65.YOxygen adsorption; III group oxides; Porous structure

Electrochemical potential of intercalation phase: Li/V₂O₅ system by Qi-Hui Wu (pp. 1713-1716).

In the communication, the use of photoelectron spectroscopy in evaluating the electrochemical potentials for intercalation phase (Li/V₂O₅ system) is presented. Two contributions, i.e. Fermi level shift and formation of surface dipole, are the main factors in the change of battery voltage during the Li intercalation. It was found that the formation of surface dipole plays more important role in the decrease of the battery voltage due to the adsorption of Li on the surface.

Keywords: Photoelectron spectroscopy; Intercalation; Electrochemical potential

Etch front roughening in wrinkly metal by Deeder Aurongzeb (pp. 1717-1721).

Scaling behavior of wrinkle evolution due to chemical etching of Au on stretchable substrate is studied by atomic force microscopy. The surfaces were etched with a small drop of KI solution. Scaling exponent α decreased with the etch time, from 0.93 to 0.62. For dynamic exponent β up to 30min we find it to be 0.16±0.05. Within the same time frame, the wavelength increases as ∼ t^0.23+−0.05 but drops at 45min as ∼ t^{−1.22+−0.42} and saturates. At this stage, we observe percolation island type features along with some wrinkles. The measured value of α at this stage is 0.62±0.02; consistent with the percolation model. The wavelength coarsening at this stage suggests the existence of chemically driven spinodal decomposition. Our obtained value of α and β is consistent with the value of z obtained from correlation length which is given by ξ= t1/^z. We find z=4.87±0.50. Our experiment suggests wrinkle formation in thin films on viscoelastic surface occurs in three stages.

Keywords: Etching; Roughening

Laser (a pulsed Nd:YAG) cladding of AZ91D magnesium alloy with Al and Al₂O₃ powders by Y.H. Liu; Z.X. Guo; Y. Yang; H.Y. Wang; J.D. Hu; Y.X. Li; A.N. Chumakov; N.A. Bosak (pp. 1722-1728).

The laser surface cladding of an AZ91D magnesium alloy with Al and Al₂O₃ powders was investigated using a pulsed Nd:YAG laser. The optimum ratio of Al to Al₂O₃ and the suitable range of laser processing parameters were identified. The resulting microstructure in the modified surface layer was examined and the wear resistance property was evaluated. The results show that the wear resistance of the laser treated samples was much superior to that of the untreated samples.

Keywords: PACS; 61.82.B; 83.60.-a; 62.20.Qp ;Magnesium alloy; Microstructure; Wear resistance

Tribological properties of chemically bonded polyimide films on silicon with polyglycidyl methacrylate brush as adhesive layer by Chufeng Sun; Feng Zhou; Lei Shi; Bo Yu; Ping Gao; Junyan Zhang; Weimin Liu (pp. 1729-1735).

Polyimide thin films, which possess good stability and film uniformity, are successfully fabricated on single crystal silicon wafers coated with a thin polymer brush by suface-initiated polymerization (SIP) as an adhesive layer. The growth kinetic of polyglycidyl methacrylate (PGMA) brush was studied by the means of ellipsometry. The nano-scale morphology and chemical composition of PGMA brush and polyimide film were studied with atomic force microscopy (AFM), Fourier transform infrared spectrum (FT-IR), and X-ray photoelectron spectroscopy (XPS). The tribological behaviors of the thin films sliding against AISI-52100 steel ball were examined on a static-dynamic friction precision measurement apparatus and UMT-2MT tribometer. The worn surface of the polyimide thin films was investigated with scanning electron microscopy (SEM). The results indicated that the chemically bonded polyimide films exhibited better friction reduction and antiwear behavior compared to the polymide films on bare silicon surface. At a load of 0.5N and sliding speed of 20mms⁻¹, the durability life of the polyimide thin films is over 25,000 sliding cycles and the friction coefficient is about 0.08.

Keywords: Surface-initiated polymerization; Polyimide; Tribological properties

Synthesis and structural properties of polypyrrole/nano-Y₂O₃ conducting composite by Qilin Cheng; Vladimir Pavlinek; Chunzhong Li; Anezka Lengalova; Ying He; Petr Saha (pp. 1736-1740).

In this work, polypyrrole/nano-Y₂O₃ conducting composite was synthesized by chemical oxidative polymerization. The composite was characterized using transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectra, UV–vis absorption spectra, X-ray photoelectron spectroscopy and electrical conductivity measurements. The results indicate that Y₂O₃ nanoparticles are almost enwrapped by polypyrrole. The addition of Y₂O₃ nanoparticles results in changes in the surface structure and conductivity of the composite. Thermogravimetric analysis shows that composite has better thermal stability than that of pure polypyrrole.

Keywords: Conducting nanocomposite; Chemical synthesis; Polypyrrole; Y; ₂; O; ₃; nanoparticles; Conductivity

Ta₂Si short time thermal oxidized layers in N₂O and O₂ to form high- k gate dielectric on SiC by A. Pérez-Tomás; N. Mestres; P. Godignon; J. Montserrat; J. Millán (pp. 1741-1744).

In this work, we report on two properties of the oxidation of tantalum silicide (Ta₂Si) on SiC substrates making this material of interest as insulator for many wide bandgap or compound semiconductors. The relatively high oxidation rate of tantalum silicide to form high- k insulator layers and its ability for being oxidized in diluted N₂O ambient in a manner similar to the oxidation in O₂ are investigated. Metal–insulator–semiconductor capacitors have been used to establish the actual applicability and constrain of the high- k insulator depending on the oxidation conditions. At 1050°C, the reduction of the oxidation time from 1h to 5min affects primordially the SiO_x interfacial layer formed between the bulk insulator and the substrate. This interfacial layer strongly influences the metal–insulator–semiconductor performances of the oxidized Ta₂Si layer. The bulk insulator basically remains unaffected although some structural differences arise when the oxidation is performed in N₂O.

Keywords: Silicon carbide; Tantalum silicide; Thermal oxidation; High-; k; dielectric; Metal–insulator–semiconductor devices

Effects of sapphire substrate annealing on ZnO epitaxial films grown by MOCVD by Yinzhen Wang; Shunquan Wang; Shengming Zhou; Jun Xu; Jiandong Ye; Shulin Gu; Rong Zhang; Qiushi Ren (pp. 1745-1747).

The annealing effects of sapphire substrate on the quality of epitaxial ZnO films grown by metalorganic chemical vapor deposition (MOCVD) were studied. The atomic steps formed on (0001) sapphire (α-Al₂O₃) substrate surface by annealing at high temperature was analyzed by atomic force microscopy (AFM). The annealing effects of sapphire substrate on the ZnO films were examined by X-ray diffraction (XRD), AFM and photoluminescence (PL) measurements. Experimental results indicate that the film quality is strongly affected by annealing treatment of the sapphire substrate surface. The optimum annealing temperature of sapphire substrates is given.

Keywords: PACS; 81.05.Dz; 81.40.−zZnO; Sapphire; Annealing; AFM; XRD; PL

Anisotropic diffusion of Cu adatoms on strained Cu (111) surface by Y.X. Wang; Z.Y. Pan; T.J. Liu; X.M. Jiang; L. Zhou; J. Zhu (pp. 1748-1752).

Diffusion of Cu atoms on a strained Cu (111) surface was studied by molecular dynamic simulation using an EAM potential. The anisotropic diffusion behaviour is found when the uniaxial strain is imposed on the surface, which does not exist under the biaxial strain. The migration of the adatom is suppressed along the tensile strain direction. The results suggest that different island morphology can be obtained by controlling anisotropic diffusion of adatoms on the strained surfaces during film growth.

Keywords: PACS; 68.43.Jk; 79.20.Rf; 81.05.BxDiffusion of adatoms; Strained Cu (1; 1; 1) surface; Thin film growth; Molecular dynamic simulation

Electrochemical luminescence of n-type ZnO semiconductor electrodes doped with rare earth metals under the anodic polarization by Toshihito Ohtake; Satoshi Hijii; Noriyuki Sonoyama; Tadayoshi Sakata (pp. 1753-1757).

Electrochemical luminescence (ECL) at n-type ZnO semiconductor electrode was measured under anodic polarization. Scanning the potential imposed on the ZnO electrode, emission was suddenly observed around +20V. Using the ZnO electrodes doped with rare earth metal ions as Sm³⁺, Eu³⁺, Dy³⁺, Ho³⁺ and Er³⁺, much brighter emission was obtained than the ECL of non-doped ZnO. These emission spectra are ascribed to the rare earth metal ions, respectively. This result would show that emission centers of doped ions were selectively excited by electrons that were injected from electrolyte to the electrode by avalanche breakdown under strong anodic bias on the ZnO.

Keywords: ECL; ZnO; Rare earth metal; Semiconductor electrode; Breakdown

Sol–gel synthesis of sub-50nm ZnO nanowires on pulse laser deposited ZnO thin films by Chang Hyun Bae; Seung Min Park; Seung-Eon Ahn; Dong-Jin Oh; Gyu Tae Kim; Jeong Sook Ha (pp. 1758-1761).

A simple synthesis route to high-quality sub-50nm ZnO nanowires is reported, utilizing ZnO thin films grown by pulse laser deposition (PLD) as seed layers. Depending upon the PLD growth conditions, the surface morphology of the ZnO nanowires on ZnO film was distinctively different whereas the diameters were almost the same. With the increase of the concentration of zinc nitrate/methenamine solution from 0.002 to 0.02M, the average diameter of the ZnO nanowire increased but remained sub-50nm. The grown ZnO nanowires showed a high crystallinity with a low defect density confirmed by a sharp photoluminescence spectrum.

Keywords: PACS; 81.07.−bZnO nanowire; Pulsed laser deposition; sub-50; nm diameter; Sol–gel synthesis

Synthesis of immunomagnetic nanoparticles and their application in the separation and purification of CD34⁺ hematopoietic stem cells by Wei Chen; Hebai Shen; Xingyu Li; Nengqin Jia; Jianming Xu (pp. 1762-1769).

The silica-coated superparamagnetic nanoparticles with the uniform diameter of about 60nm were synthesized by reverse microemulsions method. And the magnetic nanoparticles were modified with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AEAPS). The immunomagnetic nanoparticles were then successfully prepared by covalently immobilizing anti-CD34⁺ monoclonal antibodies to the surface of amino silane modified magnetic particles. The cell separation results showed that the synthesized immunomagnetic nanoparticles could rapidly and conveniently separate the CD34⁺ cells with high efficiency and specificity than normal ones. The surface morphology of separated target cells was examined by scanning electron microscope (SEM). Atomic force microscope (AFM) also characterized the magnetic materials on the surface of the separated target cells for the first time, which further confirmed that the target cells were separated by the immunomagnetic nanoparticles. The viability of the separated cells was studied by culturing method and Beckman Vi-cell viability analyst. Therefore, our experiments provided a new, direct, rapid mode to separate target cells.

Keywords: PACS; 75.50.-y; 07.79.LH; 87.17.EImmunomagnetic separation; CD34; ⁺; Monoclonal antibody (MAbs); Atomic force microscopy (AFM); Scanning electron microscopy (SEM)

The role of hydrogen peroxide in the deposition of cerium-based conversion coatings by F.H. Scholes; C. Soste; A.E. Hughes; S.G. Hardin; P.R. Curtis (pp. 1770-1780).

Cerium-based conversion coatings are progressing as an effective alternative to hazardous chromate-based systems used in the treatment of metal surfaces. However, there is still considerable debate over the mechanism by which these coatings are formed. Here, titrations of cerium-based conversion coating solutions were carried out in order to model the reactions that occur at the metal–solution interface during coating, with a particular emphasis on investigating the role of hydrogen peroxide (H₂O₂). The titration curves obtained support the proposed formation of Ce(III) peroxo complexes such as Ce(H₂O₂)³⁺ as an initial step, followed by deprotonation, oxidation and precipitation to form peroxo-containing Ce(IV) species such as Ce^(IV)(O₂)(OH)₂. The precipitates resulting from titrations were characterised by Raman spectroscopy, X-ray diffraction and thermogravimetric analysis, confirming the presence of peroxo bonds, and nano-sized CeO₂ crystallites that decreased in size with increasing H₂O₂ concentration. Characterisation of cerium conversion coatings on aluminium alloy surfaces confirmed the presence of peroxo species in the coatings, thereby supporting the titration model.

Keywords: PACS; 81.07.Bc (nanocrystalline materials); 81.15.−z (methods of deposition of films and coatings); 82.30.−b (specific chemical reactions, reaction mechanisms); 82.45.Bb (corrosion and passivation)Conversion coatings; Cerium; Hydrogen peroxide; Titrations; Raman spectroscopy; X-ray diffraction

Spray pyrolytic synthesis of large area NiO_x thin films from aqueous nickel acetate solutions by J.D. Desai; Sun-Ki Min; Kwang-Deog Jung; Oh-Shim Joo (pp. 1781-1786).

Non-stoichiometric nickel oxide thin films were prepared by pyrolytic decomposition of aerosol droplets of aqueous nickel acetate solution. Conventional un-nebulized spray pyrolysis system was used for the synthesis of thin films. The fine droplets were atomized by employing compressed air as carrier gas and allowed to decompose onto pre-heated Sn doped In₂O₃ (ITO) coated glass. The preparative parameters such as substrate temperature, solution concentration, distance from spray-nozzle to substrate, pressure of carrier air, etc., were optimized to obtain large area, uniform, thin films. The appropriate substrate temperature was selected after thermo-gravimetric analysis of nickel acetate. The temperature range of 330–420°C was investigated for pyrolysis. Structural studies using X-ray diffraction (XRD) show the formation of cubic NiO. Morphological aspects of the films as-prepared and air annealed films have been studied by employing scanning electron microscopy. The optical absorption studies give direct band gap equal to 3.61eV. The compositional analysis was carried out from the elemental depth profiles employing Auger electron spectroscopy. These indicate the formation of non-stoichiometric nickel oxide thin films. By studying I– V characteristics in alkaline electrolyte, electrocatalytic activity is tested.

Keywords: NiO; _x; Thin film; Bunsenite; Spray pyrolysis

Analysis of codeposited Gd₂O₃/SiO₂ composite thin films by phase modulated spectroscopic ellipsometric technique by N.K. Sahoo; R.B. Tokas; S. Thakur (pp. 1787-1795).

Tailoring of the refractive index of optical thin films has been a very fascinating as well as challenging topic for developing new generation optical coatings. In the present work a novel Gd₂O₃/SiO₂ composite system has been experimented and probed for its superior optical properties through phase modulated spectroscopic ellipsometry, spectrophotometry and atomic force microscopy. The optical parameters of the composite films have been evaluated using Tauc–Lorentz (TL) formulations. In order to derive the growth dependent refractive index profiles, each sample film has been modeled as an appropriate multilayer structure where each sub-layer was treated with the above TL parameterizations. All codeposited films demonstrated superiority with respect to the band gap and morphological measurements. At lower silica mixing compositions such as in 10–20% level, the composite films depicted superior spectral refractive index profile, band gap as well as the morphology. This aspect highlighted the fact that microstructural densifications in composite films can override the chemical compositions while deciding the refractive index and optical properties in such thin films.

Keywords: PACS; 42.79.Wc; 78.66.−w; 78.20.Ci; 61.16.Ch; 51.70.+f; 52.70.KzOptical coatings; Codeposition; Electron beam evaporation; Thin film multilayers; Ellipsometry; Spectrophotometry; Atomic force microscopy; Composite films

Step flow observed on top of oxidized CoAl(100) surface by V. Podgursky; V. Rose; J. Costina; R. Franchy (pp. 1796-1800).

Clean and oxidized surfaces of CoAl(100) were investigated by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), high resolution electron energy loss spectroscopy (HREELS), and scanning tunnelling microscopy (STM). The regrowth or step flow of terraces was observed at 1150K. The correlation between the growth of oxide and the step flow on the CoAl(100) surface is discussed in this paper.

Keywords: Oxidation; Alumina; Step flow; STM; LEED

Effect of thickness on the structure, morphology and optical properties of sputter deposited Nb₂O₅ films by Fachun Lai; Limei Lin; Zhigao Huang; Rongquan Gai; Yan Qu (pp. 1801-1805).

Nb₂O₅ films with the thickness ( d) ranging from 55 to 2900nm were deposited on BK-7 substrates at room temperature by a low frequency reactive magnetron sputtering system. The structure, morphology and optical properties of the films were investigated by X-ray diffraction, atomic force microscopy and spectrophotometer, respectively. The experimental results indicated that the thickness affects drastically the structure, morphology and optical properties of the film. There exists a critical thickness of the film, d_cri=2010nm. The structure of the film remains amorphous as d< d_cri. However, it becomes crystallized as d> d_cri. The root mean square of surface roughness increases with increasing thickness as d>1080nm. Widths and depths of the holes on film surface increase monotonously with increasing thickness, and widths of the holes are larger than 1000nm for the crystalline films. Refractive index increases with increasing thickness as d< d_cri, while it decreases with increasing thickness as d> d_cri. In addition, the extinction coefficient increases with increasing thickness as d> d_cri.

Keywords: PACS; 78. 20. −e; 78. 68. +m; 81. 15. CdNiobium oxide; Thickness; Optical properties; Surface roughness

On the hydrogen etching mechanism in plasma nitriding of metals by C.A. Figueroa; F. Alvarez (pp. 1806-1809).

Iron alloys and aluminum were nitrogen implanted in a controlled oxygen atmosphere and the role of hydrogen on the surface etching mechanisms studied. The surface composition was analyzed by in situ photoemission electron spectroscopy (XPS). In iron alloys, hydrogen strongly etches oxygen, improving nitrogen retention on the surface. On the other hand, hydrogen removes nitrogen from aluminum surfaces, with a deleterious effect on the nitriding effectiveness. The oxygen removal in iron alloys is associated with the catalytic effect of electrons in d-orbitals and the nitrogen removal in aluminum is associated with a steric effect.

Keywords: Surface modification; Plasma nitriding; XPS analysis; Metal alloys

Synthesis, characterization, and corrosion protection properties of poly( N-(methacryloyloxymethyl) benzotriazole- co-methyl methacrylate) on mild steel by A.P. Srikanth; A. Lavanya; S. Nanjundan; N. Rajendran (pp. 1810-1816).

The copolymers from different feed ratios of N-(methacryloyloxymethyl) benzotriazole (MMBT) and methyl methacrylate (MMA) has been synthesised using free radical solution polymerization technique and characterized using FT-IR and¹³C NMR spectroscopy. The thermal stability of the polymers was studied using theremogravimetrtic analysis (TGA). The corrosion behaviors of mild steel specimens dip coated with different composition of copolymers have been evaluated by potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) method. These electrochemical properties were observed in 0.1M HCl medium. The polarization and impedance measurements showed different corrosion protection efficiency with change in composition of the copolymers. It was found that the corrosion protection properties are owing to the barrier effect of the polymer layer covered on the mild steel surfaces. However, it was observed that the copolymer obtained from 1:1 mole ratio of MMBT and MMA exhibited better protection efficiency than other combinations.

Keywords: Methacrylic copolymers; N; -(methacryloyloxymethyl) benzotriazole; Corrosion protection; Impedance spectroscopy

A nanogravimmetric investigation of the charging processes on ruthenium oxide thin films and their effect on methanol oxidation by M.C. Santos; L. Cogo; S.T. Tanimoto; M.L. Calegaro; L.O.S Bulhões (pp. 1817-1822).

The charging processes and methanol oxidation that occur during the oxidation–reduction cycles in a ruthenium oxide thin film electrode (deposited by the sol–gel method on Pt covered quartz crystals) were investigated by using cyclic voltammetry, chronoamperometry and electrochemical quartz crystal nanobalance techniques. The ruthenium oxide rutile phase structure was determined by X-ray diffraction analysis. The results obtained during the charging of rutile ruthenium oxide films indicate that in the anodic sweep the transition from Ru(II) to Ru(VI) occurs followed by proton de-intercalation. In the cathodic sweep, electron injection occurs followed by proton intercalation, leading to Ru(II). The proton intercalation/de-intercalation processes can be inferred from the mass/charge relationship which gives a slope close to 1gmol⁻¹ (multiplied by the Faraday constant) corresponding to the molar mass of hydrogen. From the chronoamperometric measurements, charge and mass saturation of the RuO₂ thin films was observed (440ngcm⁻²) during the charging processes, which is related to the total number of active sites in these films. Using the electrochemical quartz crystal nanobalance technique to study the methanol oxidation reaction at these films was possible to demonstrate that bulk oxidation occurs without the formation of strongly adsorbed intermediates such as CO_ads, demonstrating that Pt electrodes modified by ruthenium oxide particles can be promising catalysts for the methanol oxidation as already shown in the literature.

Keywords: RuO; ₂; Sol–gel; EQCN; Methanol electrochemical oxidation

Physico-chemical, optical and electrochemical properties of iron oxide thin films prepared by spray pyrolysis by L. Dghoughi; B. Elidrissi; C. Bernède; M. Addou; M. Alaoui Lamrani; M. Regragui; H. Erguig (pp. 1823-1829).

Iron oxide thin films were prepared by spray pyrolysis technique onto glass substrates from iron chloride solution. They were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and (UV–vis) spectroscopy. The films deposited at T_s≤450°C were amorphous; while those produced at T_sub=500°C were polycrystalline α-Fe₂O₃ with a preferential orientation along the (104) direction. By observing scanning electron microscopy (SEM), it was seen that iron oxide films were relatively homogeneous uniform and had a good adherence to the glass substrates. The grain size was found (by RX) between 19 and 25nm. The composition of these films was examined by X-ray photoelectron spectroscopy and electron probe microanalysis (EPMA). These films exhibited also a transmittance value about 80% in the visible and infrared range. The cyclic voltammetry study showed that the films of Fe₂O₃ deposited on ITO pre-coated glass substrates were capable of charge insertion/extraction when immersed in an electrolyte of propylene carbonate (PC) with 0.5M LiCLO₄.

Keywords: Thin films; α-Fe; ₂; O; ₃; Spray pyrolysis; Structure; Electrochemical properties

Particle size reduction and enhanced diffusion of Fe and Pt atoms in FePt–C granular films by N addition by W.B. Mi; E.Y. Jiang; H.L. Bai (pp. 1830-1835).

N-doped FePt–C nanocomposite films were fabricated using facing-target sputtering method under different N₂ partial pressures ( P_N) at room temperature. Annealing at 650°C turns the amorphous films into ordered structures. Nitrogen doping not only make the ordering of FePt particles easier than the ordering in FePt–C films, due to the enhanced diffusivity of Fe and Pt atoms, but also effectively limits the growth of the FePt particles during the thermal induced ordering, especially for the annealed films fabricated at P_N=40%, where the average size of well-isolated FePt particles is only ∼8nm. The particle size reduction and the enhanced diffusion of Fe and Pt atoms can be ascribed to the desorption of doped N atoms and dissociation of FeN bonds during annealing. The room-temperature coercivity of the samples decreases with the P_N due to the particle size reduction and thus the enhancement of the thermal agitation for small particles during the magnetizing procedure.

Keywords: PACS; 81.07.−b; 72.80.Tm; 75.75.+a; 75.70.AkNanocomposite/granular films; FePt; L; 1; ₀; phase; Phase separation

Studies on fabrication of Ag/Tl₂Ba₂Ca₂Cu₃O₁₀/CdSe heterostructures with electrochemical technique by P.M. Shirage; D.D. Shivagan; Young-Ha Kim; S.H. Pawar (pp. 1836-1842).

The Ag/Tl₂Ba₂Ca₂Cu₃O₁₀/CdSe heterostructure was fabricated at room temperature by soft electrochemical processing technique for the first time. The formation of the heterostructure with non-diffusive interfaces was confirmed by X-ray diffraction. The crystallite sizes determined for Tl-2223 and CdSe films were 33nm and 25nm, respectively. The Tl₂Ba₂Ca₂Cu₃O₁₀ film electrodeposited onto Ag-substrate has shown the superconducting transition temperature T_c at 116.5K and J_c=2.1×10³A/cm². These values were found to improve after the deposition of CdSe onto Ag/Tl-2223 films. The effect of red He–Ne laser irradiation on the superconducting properties of heterostructure are studied and discussed at length in this paper.

Keywords: PACS; 81.15.Pq; 74.72.Fq; 78.40.Fy; 74.80.Dm; 84.37; 73.40Electrodeposition; Tl-based cuprate; Semiconductor; Nano-heterostructures; Electrical properties

Enhanced cleaning of photoresist film on a transparent substrate by backward irradiation of a Nd:YAG laser by J.H. Kim; Y.J. Suh; S.S. Kim (pp. 1843-1848).

Laser cleaning of a photoresist (PR) on a glass substrate using ns-pulsed Nd:YAG laser was studied. The direction of the substrate facing the laser beam was varied as a main parameter as well as the power of the laser beam. The backward irradiation (BWI) of the third harmonic beam (355nm) completely removed 1.2μm thick PR layer with three pulses at 1.5J/cm² leaving no residues behind; while the forward irradiation (FWI) at the same condition just partially cleaned it. To investigate the difference of removal mechanisms between irradiation directions, the size distributions of particulates generated during laser cleaning were observed using an optical particle counter. The concentration of micron-sized particulates increased with increasing laser fluence up to 1J/cm² for FWI and 0.5J/cm² for BWI and then decreased at higher fluences because the target was a very thin film. The concentration of larger particulates for BWI was much higher than that for FWI implying the difference in removal mechanisms. In consideration of the size characteristics of the particulates and the temperature profiles of the PR layer, the most probable distinct mechanism for the BWI would be a blasting due to high temperature at the PR/glass interface. The particulate number concentration decreased rapidly after the completion of cleaning, suggesting that the measurement of the particulate concentration could detect the progress of the cleaning. Our results demonstrated that the backward irradiation will be useful for the laser cleaning of film-type contaminants on an optically transparent substrate.

Keywords: PACS; 79.20.Ds; 81.65.Cf; 52.38.Mf; 81.20Rg; 92.60.MtLaser cleaning; Photoresist; Glass substrate; Particle monitoring; Backward irradiation

Structure and frictional properties of Langmuir-Blodgett films of Cu nanoparticles modified by dialkyldithiophosphate by Jun Xu; Shuxi Dai; Gang Cheng; Xiaohong Jiang; Xiaojun Tao; Pingyu Zhang; Zuliang Du (pp. 1849-1855).

Langmuir-Blodgett (LB) films of dialkyldithiophosphate (DDP) modified Cu nanoparticles were prepared. The structure, microfrictional behaviors and adhesion of the LB films were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and atomic/friction force microscopy (AFM/FFM). Our results showed that the modified Cu nanoparticles have a typical core–shell structure and fine film-forming ability. The images of AFM/FFM showed that LB films of modified Cu nanoparticles were composed of many nanoparticles arranged closely and orderly and the nanoparticles had favorable behaviors of lower friction. The friction loop of the films indicated that the friction force was affected prominently by the surface slope of the Cu nanoparticles and the microfrictional behaviors showed obvious “ratchet effect�?. The adhesion experiment showed that the modified Cu nanoparticle had a very small adhesive force.

Keywords: Cu nanoparticles; Surface modification; Langmuir-Blodgett (LB) film; Frictional properties; Atomic/friction force microscopy

Defect structure and dielectric properties of Bi-based pyrochlores probed by positron annihilation by Huiling Du; Xi Yao; Xianfeng Zhang; Huimin Weng (pp. 1856-1860).

Positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques have been performed to identify structural defects of the bismuth based pyrochlore systems with generic formula (Bi_1.5Zn_0.5)(Zn0.5− x_/3Ti_xNb1.5−2 x_/3)O₇ ( x=0, 0.25, 0.5,1.0, 1.5). We found that all studied compounds contain substantial amount of the lattice vacancy defects, the variation of the annihilation lifetime suggests that the defects structure undergoes significant changes. The complex defects could be produced with increasing content of Ti, resulting in a drop in the intensity I₂ in the Ti-rich sample. At 1MHz their dielectric constant ( ɛ′) varies from 150 for Ti-poor system to 210 for Ti-rich system and loss tangent (tan δ) remains rather low level. The high dielectric constant response of the BZTN ceramics is attributed to loosening state of cations located in the center of octahedral, so favor off-center displacement. The occurrence of complex defects help to enhance the dielectric constant.

Keywords: PACS; 78.70.Bj; 74.62.Dh; 77.22.ChPositron annihilation; Pyrochlore; Complex defects; Dielectric constant

Formation of functional groups on graphite during oxygen plasma treatment by Uroš Cvelbar; Boštjan Markoli; Igor Poberaj; Anton Zalar; Ladislav Kosec; Savo Spaić (pp. 1861-1865).

Improved sample wettability was obtained by oxygen plasma functionalization of pyrolytic graphite. The samples were exposed to highly dissociated oxygen plasma with the density of 1×10¹⁶m⁻³, the electron temperature of about 5.5eV and the density of neutral oxygen atoms of 8×10²¹m⁻³ for 20s. The surface wettability was measured by a contact angle of water drop. The contact angle dropped from original 112° down to about 1°. The functional groups were detected by XPS analyses. The survey spectrum showed a substantial increase of oxygen concentration on the surface, while high-resolution analyses showed additional oxygen was bonded onto the graphite surface in the form of C–O polar functional group responsible for the increase of the surface energy.

Keywords: PACS; 81.65.−b; 81.65.CfOxygen plasma; Surface functionalization; Oxygen; Graphite

Bulk periodic structures formation on monocrystalline silicon surface under the action of compression plasma flows by V.M. Astashynski; S.I. Ananin; A.S. Emelyanenko; E.A. Kostyukevich; A.M. Kuzmitzky; S.P. Zhvavy; V.V. Uglov (pp. 1866-1872).

The results of numerical simulation of monocrystalline silicon melting and crystallization under the action of compression plasma flow generated by quasistationary plasma accelerators with regard to phase transformations based on Kolmogorov equation are presented. Temporal and spatial characteristics of melting and crystallization processes for pulses of various forms are discussed. Based on data received and estimates made, the conclusion on substantial role of thermoelectric instability in bulk periodic structures formation was made.

Keywords: PACS; 52.40.−w; 52.50.Dg; 52.75−d; 81.05−tPlasma processing; Plasma accelerators (guns); Surface modification; Melting; Crystallization

Structural, morphological, wettability and thermal resistance properties of hydro-oleophobic thin films prepared by a wet chemical process by A.R. Phani (pp. 1873-1881).

The structural properties of fluorine containing polymer compounds make them highly attractive materials for hydro-oleophobic applications. However, most of these exhibit low surface energy and poor adhesion on the substrates. In the present investigation, crack free, smooth and uniform thin films of poly[4,5-difluoro-2,2-bis(trifluoromethyl)-1,3-dioxole]-co-tetrafluoroethylene (TFD-co-TFE) with good adhesion have been deposited by wet chemical spin-coating technique on polished AISI 440C steel substrates. The as-deposited films (xerogel films) have been subjected to annealing for 1h at different temperatures ranging from 100 to 500°C in an argon atmosphere. The size growth of the nano-hemispheres increased from 8nm for xerogel film to 28nm for film annealed at 400°C. It was found that as the annealing temperature increased from 100 to 400°C, nano-hemisphere-like structures were formed, which in turn have shown increase in the water contact angle from 122° to 147° and oil (peanut) contact angle from 85° to 96°. No change in the water contact angle (122°) has been observed when the films deposited at room temperature were heated in air from 30 to 80°C as well as exposed to steam for 8 days for 8h/day indicating thermal stability of the film.

Keywords: Wet chemical process; Spin coating; Nano-hemispheres; Roughness; Xerogel; Annealing temperature

TEM monitoring of silver nanoparticles formation on the surface of lead crystal glass by C. Gil; M.A. Villegas; J.M. Fernández Navarro (pp. 1882-1888).

Silver nanoparticles have been formed on the surface of lead crystal glass by means of (i) ion-exchange of alkaline ions from the glass by Ag⁺ ions from a molten salts bath, and (ii) silica based sol–gel coatings containing silver. All experimental variables concerning both ion-exchange process and sol–gel coatings application were combined and studied as main parameters governing the reduction of Ag⁺ ions to Ag⁰ atoms and further aggregation to form nanosized colloids. The content of thermoreducing agents (arsenic or antimony oxides) in the lead crystal glass was essential to favour the reduction of silver ions to form nanoparticles. Optimal experimental conditions to be used for the obtaining of surface silver nanoparticles were determined. TEM was used as the principal characterisation technique for direct observation of the nanoparticles generated. The size of silver colloids varied in the 20–300nm range for ion-exchanged samples and in the 10–80nm range for sol–gel coated samples.

Keywords: PACS; 61.43.Fs; 61.46.Df; 68.37.LpTEM; Silver; Lead glass; Nanoparticles; Ion-exchange; Sol–gel

Substrate effects on the oxygen gas sensing properties of SnO₂/TiO₂ thin films by Hsiao-Ching Lee; Weng-Sing Hwang (pp. 1889-1897).

In this study, SnO₂/TiO₂ thin films are fabricated on SiO₂/Si and Corning glass 1737 substrates using a R.F. magnetron sputtering process. The gas sensing properties of these films under an oxygen atmosphere with and without UV irradiation are carefully examined. The surface structure, morphology, optical transmission characteristics, and chemical compositions of the films are analyzed by atomic force microscopy, scanning electron microscopy and PL spectrometry. It is found that the oxygen sensitivity of the films deposited on Corning glass 1737 substrates is significantly lower than that of the films grown on SiO₂/Si substrates. Therefore, the results suggest that SiO₂/Si is an appropriate substrate material for oxygen gas sensors fabricated using thin SnO₂/TiO₂ films.

Keywords: Oxygen sensor; SnO; ₂; /TiO; ₂; thin film; Gas sensor; Photocatalytic effect

Mesoporous nanotube aggregates obtained from hydrothermally treating TiO₂ with NaOH by Chien-Cheng Tsai; Jun-Nan Nian; Hsisheng Teng (pp. 1898-1902).

Nanotube aggregates with high porosity were prepared from hydrothermal treatment of TiO₂ particles in NaOH at 130°C, followed by HCl rinsing to different pH values. Pore structure of the aggregates, which were mainly mesoporous, was characterized by analyzing the N₂ sorption isotherm with different methods including the t-plot and density function theory. The surface area, pore volume and mean pore size of the aggregates increased with the rinsing acidity to reach a maximum (e.g. 400m²/g in surface area) at pH 1.6 and then decreased with further increase of the acidity. The crystalline phase and composition of the aggregates were, as well, significantly affected by the acidity of the post-treatment rinsing. Large-surface area aggregates were of loosely-attached nanotubes, composed of both anatase TiO₂ and H₂Ti₂O₅·H₂O, obtained under a mildly acidic rinsing condition, while basic or highly acidic conditions resulted in the formation of closely coagulated dense structures consisting of different crystalline phases.

Keywords: Nanotube; Titanate; Titania; Nitrogen sorption; Pore size distribution; Mesoporous structure; Hydrothermal treatment

Synthesis and characterization of Al–N codoped p-type ZnO epitaxial films using high-temperature homo-buffer layer by Q.Y. Zhu; Z.Z. Ye; G.D. Yuan; J.Y. Huang; L.P. Zhu; B.H. Zhao; J.G. Lu (pp. 1903-1906).

Al–N codoped p-type ZnO thin films have been prepared by DC magnetron reactive sputtering reproducibly using a high-temperature (HT) homo-buffer layer. The influence of HT buffer layer deposition time ( T_ht) on film properties was investigated by X-ray diffraction (XRD), scanning electron micro-spectra (SEM) and Hall measurement. The Al–N codoped ZnO film was improved evidently in its crystal quality by varying the value of T_ht. Results of Hall effect showed that all of the Al–N codoped ZnO thin films were p-type conduction and had resistivity mainly below 50Ωcm. The optimum deposition time of HT buffer layer is around 3min from the comprehensive consideration of structural, electrical, and optical properties. The obtained ZnO thin film can meet the need of application in optoelectronic devices based on ZnO.

Keywords: PACS; 61.72.V; 72.80.E; 73.61.G; 78.66.HZnO thin films; Al–N codoping method; p-Type conduction; DC magnetron reactive sputtering

The effect of temperature on the preparation of electrochromic nickel oxide by an electroless method by Wei Feng Chen; Shu Yii Wu (pp. 1907-1911).

The advantages of nickel oxide as an electrochromic material are due to its good contrast of transmittance and its suitable use as a secondary electrochrome. Compared to other methods of depositing eletrochromic nickel oxide, coating nickel oxide by electroless is simple and easy to scale-up for industrial application. This study presents the preparation of nickel oxide film on an ITO substrate by an electroless method and oxidizing it with heat treatment. The influence of oxidizing temperature in heat treatment procedures is notable. The morphology of the film was analyzed by a scanning electron microscope (SEM) and X-ray diffraction (XRD). Heat temperature at 380°C obtained optimal of electrochromic properties. The transmittance difference (Δ T) of the film at 630nm was maintained at 69%, and the amount of transferred charge during cyclic voltammetry was approximately 0.8mC/cm² after 1000 cycles of redox, which was operated between −1.5 and +1.5V potential step. The degradation of the film was decreased by increasing the oxidizing temperature. The evidences showed electrochromic abilities of nickel oxide were affected by heat-treatment procedures. All these analyses provided a novel method for preparing the electrochromic nickel oxide in a low-cost way.

Keywords: Nickel oxide; Electrochromic; Electroless; Oxidizing temperature

Photocatalytic oxidation of natural organic adsorbates on anatase TiO₂ films observed by infrared adsorption spectroscopy with a multiple internal reflection geometry by F. Hirose; M. Kurita; Y. Kimura; M. Niwano (pp. 1912-1916).

Photocatalytic oxidation of organic adsorbates on anatase TiO₂ films has been examined in different atmospheres of humid air, dry air and vacuum. The photocatalytic oxidation was observed by IR absorption spectroscopy (IRAS) with a multiple-internal-reflection (MIR) geometry. The photocatalytic oxidation is the fastest in the air at a humidity of 70% where oxygen and water vapor are consuming to produce OH radicals and O₂⁻ anions on the TiO₂ surface with the UV exposure. In the dry air, a rate of the photocatalytic oxidation is almost 30% of that in the humid air, where only O₂⁻ anions oxidize the organic adsorbates. In vacuum, on the other hand, it is negligible, which suggests that adsorbed H₂O molecules do not play an important role in the photocatalytic reaction. It is suggested that an addition of the water vapor is necessary to achieve the higher catalytic activity.

Keywords: PACS; 68.47.GhTiO; ₂; Photocatalyst; FTIR

High work function of Al-doped zinc-oxide thin films as transparent conductive anodes in organic light-emitting devices by T.W. Kim; D.C. Choo; Y.S. No; W.K. Choi; E.H. Choi (pp. 1917-1920).

Deposition of Al-doped ZnO (AZO) films with various film thicknesses on glass substrates was performed to investigate the feasibility of using AZO films as anode electrodes in organic light-emitting devices (OLEDs). The electrical resistivity of the AZO films with a 180-nm thickness was 4.085×10⁻²Ωcm, and the average optical transmittance in the visible range was 80.2%. The surface work function for the AZO films, determined from the secondary electron emission coefficients obtained with a focused ion beam, was as high as 4.62eV. These results indicate that AZO films grown on glass substrates hold promise for potential applications as anode electrodes in high-efficiency OLEDs.

Keywords: PACS; 68. 55.jk; 72; 15.Eb; 73. 20.AtAl-doped ZnO; Resistivity; Transmittance; Work function; Organic light-emitting devices

Segregation of silicone acrylate from acrylate mixture at resin–mold interface and its effect on UV embossing by W.X. Zhou; Mary B. Chan-Park (pp. 1921-1928).

When silicone diacrylate was added in small amount (<5wt.%) to ultraviolet (UV) curable formulations containing other oligomeric diacrylates, there was segregation of the silicone additive at the solid substrate–formulation interface. The amount was quantified by X-ray photoelectron spectroscopy measurement of the UV cured film surface composition. The effect of silicone diacrylate concentration, resin formulation and substrate polarity on silicone surface excess was systematically studied. Young's–Gibbs adsorption theory was applied to the prediction of the silicone surface excess at the solid substrate interface for these oligomeric mixtures. Further, we proposed a simplified Young's–Gibbs adsorption theory equation to predict the variation of surface excess from only formulation surface tension and substrate critical surface tension. The selective segregation is beneficial to demolding in UV embossing since only small amount of release added can result in large decrease of the mold–resin interfacial energy difference leading to easy demolding and high replication fidelity.

Keywords: Silicone; Surface segregation; UV embossing; Diacrylate; Gibbs adsorption

Influence of dentin pre-treatment with NaOCl on the morphology of adhesive interface of self-etching adhesive systems by Carina Sinclér Delfino; Regina Guenka Palma-Dibb (pp. 1929-1933).

The aim of this in vitro study was to evaluate the influence of pre-treatment using NaOCl in the morphology of dentin/resin interface. The three self-etching adhesive systems were selected: One-Up Bond F (Tokuyama, Tokyo, Japan), Prime & Bond NT/NRC (Dentsply, Konstanz, Germany) and Clearfil SE Bond (Kuraray, Osaka, Japan). Nine dentin disks were used in this study. Half disk was treated strictly following manufacturers’ instructions (control groups). The other half was treated with a solution of 2.5% NaOCl (experimental groups). After the bonding protocols were accomplished, a low viscosity resin (Flow-it/Jeneric Pentron) was inserted and light-cured. Specimens were prepared for SEM. Morphological aspects were observed, comparing both the groups. The analysis of the photomicrographs revealed formation of a hybrid layer for both controls groups along the interface. The experimental groups showed a resin/dentin interface more irregular and produced topographical features with funnel-shaped dentin tubules. Areas with absence of hybrid layer formation were observed, mainly for One-Up Bond F, although tubules their lateral branches were filled with Prime & Bond NT/NRC and Clearfil Se Bond adhesive systems. It was concluded that the use of NaOCl influenced negatively in the formation of the hybrid layer, mainly for the One-Up Bond F.

Keywords: Hybrid layer; Collagen layer; Sodium hypochlorite

ZrB₂-based Ohmic contacts to p-GaN by Lars Voss; S.J. Pearton; F. Ren; I.I. Kravchenko (pp. 1934-1938).

The annealing temperature dependence of contact resistance and layer stability of ZrB₂/Ti/Au and Ni/Au/ZrB₂/Ti/Au Ohmic contacts on p-GaN is reported. The as-deposited contacts are rectifying and transition to Ohmic behavior for annealing at ≥750°C, a significant improvement in thermal stability compared to the conventional Ni/Au Ohmic contact on p-GaN, which is stable only to <600°C. A minimum specific contact resistance of ∼2×10⁻³Ωcm⁻² was obtained for the ZrB₂/Ti/Au after annealing at 800°C while for Ni/Au/ZrB₂/Ti/Au the minimum value was 10⁻⁴Ωcm⁻² at 900°C. Auger Electron Spectroscopy profiling showed significant Ti, Ni and Zr out diffusion at 750°C in the Ni/Au/ZrB₂/Ti/Au while the Ti and Zr intermix at 900°C in the ZrB₂/Ti/Au. These boride-based contacts show promise for contacts to p-GaN in high temperature applications.

Keywords: ZnO; Ohmic contacts

Segregation of H, C and B to Σ=5 (013) α-Fe grain boundary: A theoretical study by S. Gesari; B. Irigoyen; A. Juan (pp. 1939-1945).

The ASED-MO theory is used to study the effects of H and the HC and HB pairs in the electronic structure of a Fe grain boundary (GB). The results obtained for H in a GB model are consistent with its behavior as a chemical embrittler. The total energies calculated for FeH, FeC and FeB clusters indicate that all interstitials segregate to the GB. C has the lowest energy, followed by B, and could compete with other impurities for the site location on the GB.The results obtained for FeCH and FeBH are consistent with the observed behavior of C and B as cohesion enhancers. A strong repulsive interaction between C and H and B and H atoms is developed if they occupy the nearest interstitial site on the GB. When C or B are present, the total energies are similar to that obtained for the FeH cluster. This indicates that H is displaced from the capped trigonal prism (CTP). Also, we do not detect any CH or BH interaction.Density of states (DOS) and crystal orbital overlap population (COOP) curves are used to shed more light on the interstitial-Fe GB interaction. The existence of strong metal–metalloid bonds is shown, which are primarily due to Fe 3d, 4s and C (or B) 2s, 2p interactions.

Keywords: Computer simulation; Iron; Embrittlement; Grain boundary; Electronic structure

Studies on chelating adsorption properties of novel composite material polyethyleneimine/silica gel for heavy-metal ions by Baojiao Gao; Fuqiang An; Kangkai Liu (pp. 1946-1952).

Firstly, the coordination processes of line-type polyethyleneimine with Cu²⁺, Cd²⁺ and Zn²⁺ were studied by using visible light absorption spectroscopy and chelation conductivity titration method, and the structures of the chelates were determined. Afterwards, polyethyleneimine (PEI) was grafted onto the surface of silica gel particles via the coupling effect of γ-chloropropyl trimethoxysilane (CP), and the novel composite adsorption material PEI/SiO₂ with strong adsorption ability towards heavy-metal ions was prepared. The chelating adsorption properties of PEI/SiO₂ for Cu²⁺, Cd²⁺ and Zn²⁺ were researched by both static (batch) and dynamic (flow) methods. The experiment results show that water-soluble polyamine PEI with line-type structure reacts with Cu²⁺, Cd²⁺ and Zn²⁺ easily and quantitatively, and water-soluble chelates with four ligands are formed. The composite material PEI/SiO₂ possesses very strong chelating adsorption ability for heavy-metal ions, and the saturated adsorption amount can reach 25.94mgg⁻¹ and 50.01mgg⁻¹ for Cu²⁺ under static and dynamic conditions, respectively. The isothermal adsorption data fit to Langmuir equation, and the adsorption is typical chemical adsorption with monomolecular layer. The adsorbing ability of PEI/SiO₂ towards the three kinds of the ions follows the order of Cu²⁺>Cd²⁺>Zn²⁺. The pH value has great influence on the sorption, and at pH 6–7, the adsorption capacity is the greatest. The fact that adsorption capacity increases with temperature rising indicates the adsorbing process of PEI/SiO₂ for metal ions is endothermic. As diluted hydrochloric acid is used as eluent, the adsorbed heavy-metal ions are eluted easily from PEI/SiO₂, and the regeneration and reuse without decreasing sorption for PEI/SiO₂ are demonstrated.

Keywords: Polyethyleneimine; Heavy-metal ions; Chelating adsorption; Silica gel; Composite material

Work function of sol–gel indium tin oxide (ITO) films on glass by P.K. Biswas; A. De; L.K. Dua; L. Chkoda (pp. 1953-1959).

Indium tin oxide (ITO) films (physical thickness, 250–560±25nm) were deposited on soda lime silica (SLS) glass and silica layer coated (∼200nm physical thickness) SLS glass substrates by sol–gel technique using alcohol based precursors containing different In:Sn atomic percentages, namely, 90:10, 70:30, 50:50, 30:70. Cubic phase of In₂O₃ was observed up to 50at.% Sn while cassiterite SnO₂ phase was observed for 70at.% Sn. Work function of the films was evaluated from inelastic secondary electron cutoff of ultraviolet photoelectron spectroscopy (UPS) energy distribution curve (EDC) obtained under two experimental conditions (i) as-introduced (ii) after the cleaning of the surface by sputtering. Elemental distribution and the presence of oxygen containing contaminant and carbon contaminant of the samples were done by XPS analysis under same conditions. The work function changed little due to the presence of surface contaminants. It was in the range, 3.9–4.2eV (±0.1eV).

Keywords: PACS; 81.40.−z; 82.65.− i; 68.55.LnSol–gel; ITO films; UPS; XPS; Work function

Microstructure array on Si and SiOx generated by micro-contact printing, wet chemical etching and reactive ion etching by Hua Zhang; Nabil A. Amro; Sandeep Disawal; Robert Elghanian; Roger Shile; Joseph Fragala (pp. 1960-1963).

A method, combining micro-contact printing (μCP), wet chemical etching and reactive ion etching (RIE), is reported to fabricate microstructures on Si and SiOx. Positive and negative structures were generated based on different stamps used for μCP. The reproducibility of the obtained microstructures shows the methodology reported herein could be useful in Micro-Electro-Mechanical Systems (MEMS), optical and biological sensing applications.

Keywords: Micro-contact printing; Wet chemical etching; Reactive ion etching; Silicon; Silicon oxide

Deposition of sputtered iridium oxide—Influence of oxygen flow in the reactor on the film properties by E. Slavcheva; U. Schnakenberg; W. Mokwa (pp. 1964-1969).

Thin films of iridium oxide have been deposited by reactive magnetron sputtering. The influence of oxygen partial pressure in the sputtering plasma on the composition, surface structure and morphology of the films has been studied by XRD, SEM and AFM analysis. An optimal combination of sputtering parameters yields stable microporous amorphous films with highly extended fractal surface. The electrochemical properties of these films have been investigated in view of their application as catalysts for water splitting, using the electrochemical techniques of cyclovoltammetry, electrochemical impedance spectroscopy, and steady state polarization. The SIROFs have shown an excellent electrochemical reversibility and a high catalytic activity toward the oxygen evolution reaction in 0.5M H₂SO₄. A current density of 150mAcm⁻² at potential of 1.7V (versus Ag/AgCl) has been obtained at catalyst load of only 100μgcm⁻². These results combined with the established long-term mechanical stability of the sputtered iridium oxide films (SIROFs) proved the advantages of the reactive magnetron sputtering as simple and reliable method for preparation of catalysts with precisely controlled composition, loading, and surface characteristics.

Keywords: Sputtered iridium oxide; Generic curves; Electrocatalysis; Water splitting

The influence of UV irradiation on surface composition of collagen/PVP blended films by A. Sionkowska; M. Wisniewski; H. Kaczmarek; J. Skopinska; P. Chevallier; D. Mantovani; S. Lazare; V. Tokarev (pp. 1970-1977).

The surface chemical composition and surface properties of collagen/poly(vinyl pyrrolidone) (PVP) blended films before and after UV irradiation ( λ=254nm) were investigated using X-ray Photoelectron Spectroscopy (XPS), FTIR–ATR spectroscopy and Atomic Force Microscopy (AFM).The XPS results showed that collagen is enriched on the surface of the collagen/PVP blend. The surface composition of the collagen film was changed more by UV irradiation than the surface composition of the collagen/PVP blend.FTIR–ATR spectra showed that the positions of the amide bands in collagen are more altered after UV irradiation than those for the collagen/PVP blends.AFM images showed that the collagen surface is ordered contrary to PVP. The blend surface was similar to the pure collagen surface and confirms that there is more collagen present at the surface (higher concentration of collagen at the surface compared to PVP). UV irradiation caused only the small changes in the surface morphology of the collagen/PVP films. All of the results confirm that the surface of the collagen/PVP blend is more photoresistant than collagen.

Keywords: Collagen; PVP; Polymer blends; Surface properties; UV-irradiation; XPS

Thionin adsorption on silicon (1 0 0): Structural analysis by R. Miotto; J.F. R. Cunha; S.W. da Silva; M.A. G. Soler; P.C. Morais; A.C. Ferraz; Dayane B. Tada; D.F. S. Petri; Mauricio S. Baptista (pp. 1978-1982).

In the search of new photoactive species that may be of use either in energy conversion or in photodynamic therapy, we studied the functionalization of silicon (1 0 0) with thionin using the glutaraldehyde coupling reaction. Surface properties were obtained by ellipsometric measurements, atomic force microscopy, and luminescence spectroscopy, which indicated the formation of a well organised monolayer in the silicon surface. In addition, the comparison of Raman spectroscopy data with first-principles pseudopotential calculations of the vibrational modes of the thionin molecule also indicate the formation of a monolayer of intact thionin molecules. Therefore, the simple functionalization process (involving only mild aqueous solution chemistry) described here works well and can be used to construct smooth monolayers of photoactive molecules with functional amine groups.

Keywords: Thionin; Raman spectroscopy; Ellipsometry; Scanning force microscopy; Chemisorption; Surface electronic phenomena

In situ preparation of hydrophobic CaCO₃ in the presence of sodium oleate by Ye Sheng; Bing Zhou; Chengyu Wang; Xu Zhao; Yanhui Deng; Zichen Wang (pp. 1983-1987).

Hydrophobic CaCO₃ particles were directly prepared via carbonation of Ca(OH)₂ slurry in the presence of sodium oleate at room temperature. Sodium oleate was used to modify the surface property of CaCO₃ particles. The measurement of relative contact angle and active ratio indicated that CaCO₃ samples were hydrophobic. DTG, FT-IR and TEM analysis of the obtained product indicated that the hydrophobic property was attributed to the deposition of calcium oleate, produced in the reaction mixture, onto the surface of calcium carbonate particles. They were covered on the CaCO₃ crystals surface and modified their surface property; at the same time they own CC bonds and could be polymerized or copolymerized later to give a polymeric monolayer.

Keywords: In situ; Hydrophobic; CaCO; ₃; Sodium oleate

IR and XPS investigation of visible-light photocatalysis—Nitrogen–carbon-doped TiO₂ film by Jing Yang; Haizan Bai; Xingchen Tan; Jianshe Lian (pp. 1988-1994).

To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Nitrogen and carbon doping TiO2− x−_yN_xC_y films were obtained by heating the TiO₂ gel in an ionized N₂ gas and then were calcined at 500°C. The TiO2− x−_yN_xC_y films have revealed an improvement over the TiO₂ films under visible light (wavelength, 500nm) in optical absorption and photocatalytic activity such as photodegradation of methyl orange. X-ray photoemission spectroscopy, infrared spectrum and UV–visible (UV–vis) spectroscopy were used to find the difference of two kinds of films. Nitrogen and carbon doped into substitutional sites of TiO₂ has been proven to be indispensable for band-gap narrowing and photocatalytic activity.

Keywords: Nitrogen–carbon-doped TiO; ₂; Visible-light; Oxygen vacancy; Photocatalysis

On the surface trapping parameters of polytetrafluoroethylene block by Guan-Jun Zhang; Kai Yang; Wen-Bin Zhao; Zhang Yan (pp. 1995-1998).

Surface flashover phenomena under high electric field are closely related to the surface characteristics of a solid insulating material between energized electrodes. Based on measuring the surface potential decaying curve of polytetrafluoroethylene (PTFE) block charged by a needle-plane corona discharge, its surface trapping parameters are calculated with the isothermal current theory, and the correlative curve between the surface trap density and its energy level is obtained. The maximum density of electron traps and hole traps in the surface layer of PTFE presents a similar value of ∼2.7×10¹⁷eV⁻¹m⁻³, and the energy level of its electron and hole traps is of about 0.85–1.0eV and 0.80–0.90eV, respectively. Via the X-ray photoelectron spectroscopy (XPS) technique, the F, C, K and O elements are detected on the surface of PTFE samples, and F shows a remarkable atom proportion of ∼73.3%, quite different from the intrinsic distribution corresponding to its chemical formula. The electron traps are attributed to quantities of F atoms existing on the surface of PTFE due to its molecular chain with C atoms surrounded by F atoms spirally. It is considered that the distortions of chemical and electronic structure on solid surface are responsible for the flashover phenomena occurring at a low applied voltage.

Keywords: Insulating material; Trapping parameter; Surface flashover; Surface potential; Surface component

The effect of oxidation on physical properties of porous silicon layers for optical applications by Parasteh Pirasteh; Joël Charrier; Ali Soltani; Séverine Haesaert; Lazhar Haji; Christine Godon; Nicolas Errien (pp. 1999-2002).

In order to understand the optical loss mechanisms in porous silicon based waveguides, structural and optical studies have been performed. Scanning and transmission electron microscopic observations of porous silicon layers are obtained before and after an oxidation process at high temperature in wet O₂. Pore size and shape of heavily p-type doped Si wafers are estimated and correlated to the optical properties of the material before and after oxidation. The refractive index was measured and compared to that determined by the Bruggeman model.

Keywords: Nanostructured silicon; Physical and optical characterisations; Oxidation effects

Effect of TiO₂ nanoparticle size on the performance of PVDF membrane by Xiaochun Cao; Jun Ma; Xuehua Shi; Zhijun Ren (pp. 2003-2010).

The comparison of the performance and morphology was carried out between neat PVDF membrane and PVDF composite membranes with nanosized TiO₂ particles of different size. The results of permeability and instrumental analysis illustrated that nanometer size obviously affected the performance and structure of the PVDF membranes. The smaller nanoparticles could improve the antifouling property of the PVDF membrane more remarkably. The surface and cross-section of the membranes were observed with an atomic force microscopy (AFM), a scanning electron microscope (SEM). The TiO₂/PVDF membrane with smaller nanoparticles had smaller mean pore size on its surface and more apertures inside the membrane. X-ray diffraction (XRD) experiments also suggested that smaller TiO₂ nanoparticles had stronger effect on the crystallization of PVDF molecules.

Keywords: PVDF membrane; Ultrafiltration; Nanoparticle; TiO; ₂; Surface

Validation of fuzzy logic method for automated mass spectral classification for mineral imaging by B. Yan; T.R. McJunkin; D.L. Stoner; J.R. Scott (pp. 2011-2017).

Imaging mass spectrometry requires the acquisition and interpretation of hundreds to thousands of individual spectra in order to map the mineral phases within heterogeneous geomatrices. A fuzzy logic inference engine (FLIE) was developed to automate data interpretation. To evaluate the strengths and limitations of FLIE, the chemical images obtained using FLIE were compared with those developed using two chemometric methods: principle component analysis (PCA) and cluster analysis (K-Means). Two heterogeneous geomatrices, a low-grade chalcopyrite ore and basalt, were imaged using a laser-desorption Fourier transform mass spectrometer. Similar mineral distribution patterns in the chalcopyrite ore sample were obtained by the three data analysis methods with most of the differences occurring at the interfaces between mineral phases. PCA missed one minor mineral phase in the chalcopyrite ore sample and did not clearly differentiate among the mineral classes of the basalt. K-Means cluster analysis differentiated among the various mineral phases in both samples, but improperly grouped some spectra in the chalcopyrite sample that only contained unanticipated high mass peaks. Unlike the chemometric methods, FLIE was able to classify spectra as unknowns for those spectra that fell below the confidence level threshold. A nearest neighbor approach, included in FLIE, was used to classify the unknowns to form a visually complete image; however, the unknowns identified by FLIE can be informative because they highlight potential problems or overlooked results. In conclusion, this study validated the fuzzy logic-based approach used in our laboratory and reveald some limitations in the three techniques that were evaluated.

Keywords: PACS; 07.05.Mh; 82.80.Nj; 91.67.GyChemical imaging; Mineral; Fuzzy logic; Principal component analysis; Cluster analysis; Laser desorption Fourier transform mass spectrometry

Calculation of the surface energy of hcp metals by using the modified embedded atom method by Jian-Min Zhang; Dou-Dou Wang; Ke-Wei Xu (pp. 2018-2024).

With MEAM, the surface energies of three kinds of representative surfaces, ( h0 l), ( h h l) and ( h k0) belong to [010], [11¯0] and [001] crystal band, respectively, have been calculated for 13 closed-packed hexagonal (hcp) metals Co, Dy, Er, Gd, Ho, Mg, Nd, Pr, Re, Sc, Tb, Tl and Zr. For all 13 hcp metals, the basal plane (001) has the minimum surface energy. So from surface energy minimization, the (001) texture should be favored in the hcp films, this is consistent with the experimental results. The fact that the short termination corresponds to much lower surface energy than long one implies the former is more stable for those surfaces having two possible terminations. Such as the prism plane (100), only the short termination was observed in experiment.

Keywords: PACS; 68.35.Md; 68.47.De; 68.55.Jkhcp metals; Surface energy; MEAM; Calculation

Adsorption structures of tetracene on the Ru(101¯0) surface by Y.H. Lu; H.J. Zhang; Y.F. Xu; B. Song; H.Y. Li; S.N. Bao; P. He (pp. 2025-2030).

Adsorption structures of tetracene on the Ru(101¯0) surface has been investigated by means of ab initio density functional theory (DFT) calculations. Several adsorption geometries of tetracene on Ru(101¯0) were examined in details. The optimized structures have an adsorption energy of 4.23eV for tetracene adsorbed between the top and the second Ru atoms rows with its long molecular axis along the[12¯10] direction, and a slightly smaller adsorption energy of 4.19eV for tetracene adsorbed with its long axis perpendicular to[12¯10], consisting well with the adsorption structures observed in the scanning tunneling microscopy (STM) measurements for tetracene overlayer on Ru(101¯0). By Comparing DOS before and after tetracene adsorption, we suggest that the coupling of the substrate d-band and the filled p-orbitals of tetracene determines tetracene adsorption on the Ru(101¯0) surface.

Keywords: PACS; 82.65.My; 71.15 Mb; 68.35.BsTetracene; Ruthenium; Adsorption structures; DFT calculations; Density of states

Studies on electrodeposition of Fe–W alloys for fuel cell applications by C.N. Tharamani; Parthasarathi Beera; V. Jayaram; Noor Shahina Begum; S.M. Mayanna (pp. 2031-2037).

Electrodeposition of Fe–W alloy has been carried out from acidic triammonium citrate (TAC) complex bath solution. The deposit is characterised by XRD, SEM, EDAX, XPS and polarization techniques. The alloys are amorphous and become partially crystalline on heat treatment. The composition (Fe/W) of elements in the coating and their oxidation states vary from the surface to the bulk of the material. The coatings exhibit as novel electrode material with low over voltage and good corrosion resistance for anodic oxidation of methanol in H₂SO₄ medium. The anodic peak current, a measure of oxidation reaction rate is considerably high on Fe–W alloy when compared to pure Fe and also the relative surface area of Fe by alloying it with W found to increase by 1200-fold.

Keywords: Electrodeposition; Fe–W alloys; Surface analysis; Anode material; Fuel cell; Corrosion resistance

Preparation, structures and photoluminescent enhancement of CdWO₄–TiO₂ composite nanofilms by Runping Jia; Guoxin Zhang; Qingsheng Wu; Yaping Ding (pp. 2038-2042).

For the first time, Cadmium tungstate (CdWO₄)–TiO₂ composite nanofilms on a glass substrate were prepared by means of the dip-coating technique, in which collodion was used as a dispersant and film-forming agent. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermo gravimetric and thermal analyses (TG/DTA), FTIR and photoluminescence (PL) methods, respectively. SEM and XRD characterization of these films indicated that CdWO₄ particles crystallized in a monoclinic wolframite-type structure whereas TiO₂ particles were Anatase phase; and both of them were well distributed in the nanofilms. FTIR spectra proved the presence of CdWO₄ on the nanofilms. Photoluminescent results showed that the emitting peak of CdWO₄ films blue shifted slightly relative to that of CdWO₄ crystal. Moreover, the PL intensity of CdWO₄–TiO₂ composite nanofilm was much higher than that of CdWO₄ nanofilm. We ascribed that the introduction of TiO₂ should be responsible for the PL enhancement.

Keywords: Nanofilms; Composite films; CdWO; ₄; TiO; ₂; Photoluminescent enhancement

Study of leading factors in formation of surface wavy structures on a rubber material by Teng-Kai Shih; Chia-Fu Chen; Jeng-Rong Ho; Chueh-Yang Liu; Fang-Tzu Chuang (pp. 2043-2049).

Wavy structures are often observed on the surface of a rubber material (polydimethylsiloxane, PDMS) covered with a thin metallic film. In this study we demonstrate that the orientation, periodicity, location of formation, and range of periodicity of the wavy structures can be regulated by three leading factors including the surface pattern, substrate hardness and the thickness of the metallic film. Results show the orientation of the wavy structures can be adjusted by the location, shape and size of the surface patterns. Enhancement of the substrate hardness can prevent forming random wavy structures. The thickness of surface metallic film significantly influenced the periodicity of the structures. Experimental results revealed an increase of the thickness of surface Au film by 50nm, the periodicity was increased roughly by 1μm. A compound structure, combining longitudinally preset patterns and transversely induced wavy structures, and a parallel wavy structure fabricated, respectively, by suitable arrangement of pattern configurations and adjustment of substrate hardness were demonstrated. The relatively simple approaches proposed here show the potential application in fabrication of designated complicate structures.

Keywords: PDMS; Wavy structure; Grating

Formation of diamond-like carbon (DLC) film on the NiTi alloys via plasma immersion ion implantation and deposition (PIIID) for improving corrosion resistance by J.H. Sui; W. Cai (pp. 2050-2055).

NiTi alloys are potentially useful in biomedical application due to their unique superelasticity and shape memory effect. However, the materials are vulnerable to surface corrosion and the most serious issue is out-diffusion of toxic Ni ions from the substrate into body tissues and fluids. In this paper, Diamond-like carbon (DLC) film is fabricated on the NiTi alloys using plasma immersion ion implantation and deposition (PIIID) at room temperature to improve their corrosion resistance and block the out-diffusion of the Ni ions. The results show that the DLC films cannot only improve the corrosion resistance of the NiTi substrate, but also effectively suppress the Ni ions release from the substrate. The reason that the corrosion resistance of the coated samples is markedly improved due to the DLC films formation is systematically investigated.

Keywords: NiTi alloys; Diamond-like carbon (DLC); Plasma immersion ion implantation and deposition (PIIID); Corrosion resistance

Field emission from nonaligned SiC nanowires by W.M. Zhou; Y.J. Wu; Eric Siu-Wai Kong; F. Zhu; Z.Y. Hou; Y.F. Zhang (pp. 2056-2058).

β-SiC nanowires with an average diameter of 8–20nm were synthesized using a simple thermal evaporation of SiO powders onto activated carbon fibers. Field emission was investigated based on the SiC nanowires deposited on a platinum film. A low turn-on field of 3.1–3.5Vμm⁻¹ was measured at an anode-sample separation of 100–140μm. This type of SiC nanowires can be applied as field emitters in displays as well as vacuum electronic devices.

Keywords: PACS; 79.70.+q; 81.16.−c; 81.07.WxSiC; Nanowires; Field emission with low turn-on field; β-Silicon carbide nanowires

Memory switching of germanium tellurium amorphous semiconductor by M.M. Abdel-Aziz (pp. 2059-2065).

The dc conductivity and switching properties of amorphous GeTe thin film of thickness 262nm are investigated in the temperature range 303–373K. The activation energy Δ E_σ, the room temperature electrical conductivity σ_RT and the pre-exponential factor σ₀ were measured and validated for the tested sample. The conduction activation energy Δ E_σ is calculated. The I– V characteristic curves of the thin film samples showing a memory switching at the turnover point (TOP) from high resistance state (OFF state) to the negative differential resistance state (NDRS) (ON state). It is found that the mean values of the threshold electrical field E_th decreased exponentially with increasing temperatures in the investigated range. The switching activation energy Δ E_th is calculated. Measurements of the dissipated threshold power P_th and the threshold resistance R_th were carried out at TOP point at different temperatures of the samples. The activation energies Δ E_R and Δ E_P caused by resistance and power respectively are deduced. The results obtained support thermal model for initiating switching process in this system.

Keywords: Amorphous semiconductor; dc conductivity; Switching phenomena

Influence of annealing atmosphere on ZnO thin films grown by MOCVD by Jingchang Sun; Tianpeng Yang; Guotong Du; Hongwei Liang; Jiming Bian; Lizhong Hu (pp. 2066-2070).

ZnO films were deposited on c-plane sapphire substrates by metal-organic chemical vapor deposition (MOCVD). Annealing treatments for as-deposited samples were performed in different atmosphere under various pressures in the same chamber just after growth. The effect of annealing atmosphere on the electrical, structural, and optical properties of the deposited films has been investigated by means of X-ray diffraction (XRD), atomic force microscope (AFM), Hall effect, and optical absorption measurements. The results indicated that the electrical and structural properties of the films were highly influenced by annealing atmosphere, which was more pronounced for the films annealed in oxygen ambient. The most significant improvements for structural and electrical properties were obtained for the film annealed in oxygen under the pressure of 60Pa. Under the optimum annealing condition, the lowest resistivity of 0.28Ωcm and the highest mobility of 19.6cm²v⁻¹s⁻¹ were obtained. Meanwhile, the absorbance spectra turned steeper and the optical band gap red shifted back to the single-crystal value.

Keywords: PACS; 68.37.Ps; 78.55.Et; 81.05.Dz; 81.15.GhXRD; Annealing atmosphere; Grain boundary; Oxygen

Growth of size-tunable periodic Ni silicide nanodot arrays on silicon substrates by S.L. Cheng; S.W. Lu; S.L. Wong; H. Chen (pp. 2071-2077).

The fabrications of size-tunable periodic arrays of nickel metal and silicide nanodots on (001)Si substrates using polystyrene (PS) nanosphere lithography (NSL) and heat treatments have been investigated. The growth of epitaxial NiSi₂ was found to be more favorable for the Ni metal nanodot arrays. The effect becomes more pronounced with a decrease in the size of the Ni nanodots. The sizes of the epitaxial NiSi₂ nanodots were tuned from 38 to 110nm by varying the diameter of the PS spheres and heat treatment conditions. These epitaxial NiSi₂ nanodots formed on (001)Si were found to be heavily faceted and the faceted structures were more prone to form at higher temperatures. Based on TEM, HRTEM and SAED analysis, the faceted NiSi₂ nanodots were identified to be inverse pyramids in shape. Compared with the NiSi₂ nanodot arrays formed using single-layer PS sphere masks, the epitaxial NiSi₂ nanodot arrays formed from the double-layer PS sphere templates exhibit larger interparticle spacings and smaller particle sizes. Since the nanoparticle sizes, shapes and interparticle spacings can be adjusted by tuning the diameter of the PS spheres, stacking conditions, and heat treatment conditions, the PS NSL technique promises to be an effective patterning method for growth of other nanostructures.

Keywords: PACS; 81.05.Je; 42.82.Cr; 81.16.Dn; 61.46.Df; 68.55.Ac; 68.55.JkNickel silicide; Nanosphere lithography; Self-assembly; Nanodots; Epitaxy; Thin films

Stabilization of discotic liquid organic thin films by ITO surface treatment by S. Archambeau; I. Séguy; P. Jolinat; J. Farenc; P. Destruel; T.P. Nguyen; H. Bock; E. Grelet (pp. 2078-2086).

Discotic liquid crystals (LCs) are promising materials in the field of electronic components and, in particular, to make efficient photovoltaic cells due to their good charge transport properties. These materials generally exhibit a mesophase in which the disk-shaped molecules can self-assemble into columns, which favorize charge displacement, and may align themselves uniformly on surfaces to form well-oriented thin films. In order to orientate such a columnar thin film on an indium tin oxide (ITO) substrate, the film is heated up to the temperature range of the isotropic liquid phase and subsequently cooled down again. This treatment may lead not only to the desired alignment, but also to dewetting, which leads to an appreciable inhomogeneity in film thickness and to short circuits during the realization of photovoltaic cells. In this article, we describe how this dewetting and the film morphology can be influenced by ITO surface treatments. The chemical modifications of the surface by these treatments were studied by X-ray photoelectron spectroscopy (XPS). Such ITO treatments are shown to be efficient to prevent thin film dewetting when combined with rapid cooling through the isotropic-to-LC phase transition.

Keywords: PACS; 61.30 Hn; 68.35 Fx; 61.30 −v; 68.55.−a; 79.60 Fr; 81.15.−zDiscotic liquid crystal; Dewetting; ITO treatments; XPS

Annealing effects on the microstructure of amorphous carbon nitride films by X.C. Wang; Z.Q. Li; P. Wu; E.Y. Jiang; H.L. Bai (pp. 2087-2092).

Amorphous carbon nitride films, prepared using a dc facing-target reactive sputtering system, were annealed at temperatures up to 650°C for 1h in vacuum. The effects of heat treatment on the films, i.e. changes in the composition and structure, were investigated. It was found that annealing at temperatures ranging from 300 to 650°C, results in the N content decreasing from ∼33at.% in the as-deposited films to ∼5at.%. The loss of N, especially those bonded to sp³C, causes the rearrangement of the film's microstructure, and the dual effects of the thermal annealing are quite noticeable: (1) annealing destroys most graphite-like structures, and more non-aromatic sp²C components and C≡N terminal structures are formed at higher annealing temperatures, contributing to a looser film's structure. (2) Annealing makes the remaining aromatic sp²C structure become more order. The results also reveal that N atoms bonded to sp³C are easily removed with the increasing temperature compared to those bonded to sp²C, which indicates that Nsp²C bonds had a higher thermal stability than Nsp³C.

Keywords: PACS; 68.60.DV; 68.55.−a; 68.37.LP; 79.60.−iThermal stability; Carbon nitride films; Microstructure; High-resolution transmission electron microscopy; X-ray photoelectron spectroscopy

Influence of Cr interlayer on the structure and optical properties of Ag films on glass substrate by magnetron sputtering by Sun Xilian; Shao Jianda (pp. 2093-2095).

Optical properties and microstructure of Ag film on glass substrate with Cr intermediate layer were studied by using spectrophotometer and XRD. The spectra results showed that introducing Cr intermediate layer reduced the surface roughness and promoted the reflectivity of Ag film. The XRD analysis showed that the crystalline grains increased and the stress decreased. The adhesion was also improved by using the tape test method.

Keywords: PACS; 42.70−a; 81.07−bAg film; Microstructure; Optical properties; Adhesion

Improving the hydrophilicity of poly(vinylidene fluoride) porous membranes by electron beam initiated surface grafting of AA/SSS binary monomers by Fu Liu; Bao-Ku Zhu; You-Yi Xu (pp. 2096-2101).

Poly(vinylidene fluoride) (PVDF) membranes were pre-irradiated by electron beam in vacuum, and then the hydrophilic sulfonate groups were introduced by the single step grafting method with binary monomer solution of acrylic acid (AA) and sodium 4-styrenesulfonate (SSS). The effect of binary monomer ratio and pH of reaction solution on the degree of grafting was investigated. The surface chemical change was characterized by Fourier transform infrared attenuated total reflection spectroscopy (FT-IR-ATR) and X-ray photoelectron spectroscopy (XPS). Morphological changes on the membrane surface were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface hydrophilicity of the modified membrane was characterized through water contact angle measurement. It was found that the water contact angle of the membrane surface decreased significantly when compared with the original one, indicating the improvement of the surface hydrophilicity.

Keywords: PVDF; Irradiation; Modification; Hydrophilicity

Surface modifications of ITO electrodes for polymer light-emitting devices by Zhong Zhi You; Jiang Ya Dong (pp. 2102-2107).

Surface modifications were performed on the indium tin oxide (ITO) substrates for polymer light-emitting devices, using the different treatment methods including solvent cleaning, hydrochloric acid treatment and oxygen plasma. The influence of modifications on the surface properties of ITO electrodes were investigated by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle, and four-point probe. The surface energies of the ITO substrates were also calculated from the measured contact angles. Experimental results demonstrate that the surface properties of the ITO substrates strongly depend on the modification methods, and oxygen plasma more effectively improves the ITO surface properties compared with the other treatments. Furthermore, the polymer light-emitting electrochemical cells (LECs) with the differently treated ITO substrates as device electrodes were fabricated and characterized. It is observed that the surface modifications on ITO electrodes have a certain degree of influence upon the injection current, luminance and efficiency, but hardly upon the turn-on voltages of current injection and light emission which are close to the measured energy gap of electroluminescent polymer. Oxygen plasma treatment on the ITO electrode yields the better performance of the LECs, due to the improvement of interface formation and electrical contact of the ITO electrode with the polymer blend in the LECs.

Keywords: PACS; 81.65.-b; 42.70.Nq; 82.47.Tp; 85.60.JbSurface modification; ITO electrode; Polymer light-emitting electrochemical cells; Polymer light-emitting device

Effect of post-annealing temperature on the microstructure and magnetic properties of Ce:YIG thin films deposited on Si substrates by Xiongtu Zhou; Wenjuan Cheng; Fangting Lin; Xueming Ma; Wangzhou Shi (pp. 2108-2112).

Amorphous Ce₁Y₂Fe₅O₁₂ (Ce:YIG) thin films deposited on single crystal Si(100) and thermally oxidized Si(100) substrates by pulsed laser deposition were annealed in the temperature range of 700–1000°C in air. The annealing temperature dependence of microstructure and magnetic properties of Ce:YIG films was studied using X-ray diffraction combined with vibrating sample magnetometer. The results show that single phase of polycrystalline Ce:YIG thin films can be obtained by the post-annealing of as-deposited films at the temperature of 700°C. However, two steps of phase segregation of Ce:YIG occur as the post-annealing temperature increases: at first, Ce:YIG is decomposed into YIG and non-magnetic CeO₂ when annealed at 800°C; then YIG continues to be decomposed forming Fe₂O₃ when the temperature is increased up to 900°C. Consequently, the saturation magnetization of Ce:YIG films decreases first and then increases with the post-annealing temperature going up, which indicates that the saturation magnetization of Ce:YIG films is mainly related to the phase composition of the films. Meanwhile, the presence of SiO₂ buffer layer can significantly enhance the saturation magnetization of Ce:YIG films.

Keywords: PACS; 81.40.Ef; 81.40.Rs; 75.70.AkCe:YIG thin film; Post-annealing; Microstructure; Magnetic property

Corrosion resistant properties of polyaniline–acrylic coating on magnesium alloy by S. Sathiyanarayanan; S. Syed Azim; G. Venkatachari (pp. 2113-2117).

The performance of the paint coating based on acrylic–polyaniline on magnesium alloy ZM 21 has been studied by electrochemical impedance spectroscopy in 0.5% NaCl solution. The polyaniline was prepared by chemical oxidative method of aniline with ammonium persulphate in phosphoric acid medium. The phosphate-doped polyaniline was characterized by FTIR and XRD methods. Acrylic paint containing the phosphate-doped polyaniline was prepared and coated on magnesium ZM 21 alloy. The coating was able to protect the magnesium alloy and no base metal dissolution was noted even after 75 days exposure to sodium chloride solution.

Keywords: Magnesium alloy; Polyaniline; Acrylic; EIS; Corrosion

The adsorption stability & inhibition by allyl-thiourea of bulk nanocrystalline ingot iron in dilute HCl solution by C.B. Shen; S.G. Wang; H.Y. Yang; K. Long; F.H. Wang (pp. 2118-2122).

The inhibitive effect of thiourea's (TU) alkyl derivative—allyl-thiourea (ATU) on the corrosion behaviors of bulk nanocrystalline and conventional polycrystalline ingot iron (BNII & CPII) was tested. Results indicate that BNII is less prone to get corrosive than its coarse grain counterpart in blank 1molL⁻¹ HCl at room temperature. When CPII and BNII were immersed for a very short time in the corrosive solution inhibited by ATU, namely, 5min, no inductive loop appears at different concentrations. When time became prolonged, for BNII, a Warburg impedance appeared. Inhibited by ATU, the electrodes composed of the samples are polarized anodically during the potentiodynamic polarization tests, the phenomena of desorption happens at the concentration of 100mgL⁻¹, but the variation between potential E_des is obvious. The inhibition effect of ATU for BNII is very limited by comparison with CPII in dilute HCl.

Keywords: Bulk nanocrystallized ingot iron; (; BNII); Thiourea and allyl-thiourea (TU & ATU); Inhibition; Hydrochloridic solution

Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells by Swapnil B. Ambade; R.S. Mane; S.S. Kale; S.H. Sonawane; Arif V. Shaikh; Sung-Hwan Han (pp. 2123-2126).

Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200°C for 1h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV–vis spectrophotometry techniques, respectively. Cu2−_xSe phase was confirmed by XRD pattern and spherical grains of 30±4 – 40±4nm in size aggregated over about 130±10nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80mW/cm² light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.

Keywords: Copper selenide thin films; XRD; Surface morphology; Optical property; Photoelectrochemical cells

Use of the direct negative Cu ion beam deposition for the control of the properties of Cu thin film by Daeil Kim (pp. 2127-2131).

Direct metal ion beam deposition (DMIBD) technique for Cu thin film metallization is characterized. With suitable operating conditions, secondary Cu⁻ ion yield, ion/atom arrival rate ratio, ion beam energy spreads were optimized at 15%, 0.3, and 10%, respectively.After optimization of DMIBD system, the effect of Cu ion beam energy on the resistivity, adhesion strength, and surface morphology of Cu thin film was investigated. TEM micrograph shows that the film prepared at 75eV was polycrystalline, while the film prepared at 0eV was vertical columnar structure.As ion beam energy is increased from 25 to 75eV, the resistivity is decreased from 6.21 to 2.09μΩcm, while the critical load to cause adhesion failure was increased to about 13N at 200eV, which is four-times higher that that of 25eV.

Keywords: PACS; 41.75C; 34.50.DCopper; Ion bombardment; TEM; AFM; Adhesion

Microstructure and properties of Ni–Co/nano-Al₂O₃ composite coatings by pulse reversal current electrodeposition by L.M. Chang; M.Z. An; H.F. Guo; S.Y. Shi (pp. 2132-2137).

Ni–Co/nano-Al₂O₃ (Ni–Co/Al₂O₃) composite coatings were prepared under pulse reversal current (PRC) and direct current (dc) methods respectively. The microstructure of coatings was characterized by means of XRD, SEM and TEM. Both the Ni–Co alloy and composite coatings exhibit single phase of Ni matrix with face-centered cubic (fcc) crystal structure, and the crystal orientation of the Ni–Co/Al₂O₃ composite coating was transformed from crystal face (200) to (111) compared with alloy coatings. The hardness, anti-wear property and macro-residual stress were also investigated. The results showed that the microstructure and performance of the coatings were greatly affected by Al₂O₃ content and the electrodeposition methods. With the increasing of Al₂O₃ content, the hardness and wear resistance of the composite coatings enhanced. The PRC composite coatings exhibited compact surface, high hardness, better wear resistance and lower macro-residual stress compared with that of the dc composite coatings.

Keywords: Pulse reversal electrodeposition; Ni–Co/nano-Al; ₂; O; ₃; composite coating; Microstructure; Hardness; Wear

Synthesis of LECBD grown cluster assembled SeO₂ thin films by S. Rath; K. Das; S.N. Sarangi; A.K. Dash; S.K. Ray; S.N. Sahu (pp. 2138-2142).

Cluster assembled selenium oxide (SeO₂) thin films, as a function of oxygen flow pressure (OFP) have been synthesized by a low energy cluster beam deposition (LECBD) technique. The OFP dependent surface morphology leading to well separated nanoclusters (size ranging from 50 to 200nm) and fractal features are confirmed from transmission electron microscopic (TEM) measurements. A diffusion limited aggregation (DLA) mediated fractal growth with dimension as 1.71±0.01 has been observed for high OFP (60mbar). Structural analysis by glancing angle X-ray diffraction (GXRD) and selected area diffraction (SAD) studies identify the presence of tetragonal phase SeO₂ in the deposit. Micro-Raman studies indicate the shifts in bending and stretching vibrational phonon modes in cluster assembled SeO₂ as compared to their bulk counter part due to the phonon confinement effect.

Keywords: PACS; 61.46.+w; 81.15.Ef; 81.16.-c; 68.55.JkClusters; SeO; ₂; Fractal; Phonon confinement

Influence of charged particle bombardment and sputtering parameters on the properties of HfO₂ films prepared by dc reactive magnetron sputtering by Xin Liu; Dejie Li (pp. 2143-2147).

HfO₂ films prepared on glass substrates by dc reactive magnetron sputtering in an Ar+O₂ atmosphere are investigated. The films are polycrystallized with a pure monoclinic phase, and the crystallization strongly relates to the technology environment. Charged particle bombardment mainly caused by negative oxygen ions during sputtering on the films results in rougher surface morphology and worse crystalline property. Influence of sputtering pressure, substrate temperature and Ar:O₂ flow ratio is studied. The main orientations of the films are (−111) and (111). The (−111) orientation is stable, but (111) orientation is very sensitive to the sputtering condition, and it can be suppressed effectively by introducing charged particle bombardment, lowing sputtering pressure and increasing oxygen concentration.

Keywords: HfO; ₂; Magnetron sputtering; Crystalline; Charged particle bombardment

Fabrication of material-independent morphology gradients for high-throughput applications by Tobias P. Kunzler; Tanja Drobek; Christoph M. Sprecher; Martin Schuler; Nicholas D. Spencer (pp. 2148-2153).

Gradient surfaces allow rapid, high-throughput investigations and systematic studies in many disparate fields, including biology, tribology and adhesion. We describe a novel method for the fabrication of material-independent morphology gradients, involving a two-step process of particle erosion followed by a chemical polishing procedure that preferentially removes features with a small radius of curvature as a function of time. Gradients are fabricated on aluminium surfaces, but they may be readily transferred to other materials via a replication technique, which allows for the production of identical roughness gradient samples with any chosen surface chemistry. The gradients have been characterized by means of scanning electron microscopy and optical profilometry. Standard roughness parameters (Ra, Rq, Rz, Sm and Sk) were calculated from optical profilometry data. The roughness has also been assessed over different wavelength windows by means of a fast Fourier transformation approach.

Keywords: Surface roughness; Gradient; FFT; Window roughness; High-throughput; Replicas

Morphology and structure of gold–lithium niobate thin film: A laboratory source X-ray scattering study by S. Hazra (pp. 2154-2157).

Laboratory source X-ray scattering set-up has been used to determine the complete morphology and structure of an optically important composite thin film. Analysis of grazing incidence small angle X-ray scattering, X-ray reflectivity and powder diffraction data of Au/LiNbO₃ thin film prepared by sequential deposition of gold and lithium niobate on float glass substrate suggest that the Au-nanocrystallites are dispersed in amorphous medium, which although have average separation but do not have any long range periodicity other than growth or z-direction. The morphology of the nanocomposite thin film determined through X-ray scattering measurements agrees well with the measured optical absorption.

Keywords: PACS; 68.55.−a; 61.10.−I; 61.46.+w; 78.67.BfThin film structure and morphology; X-ray diffraction and scattering; Clusters; Nanoparticles; and nanocrystalline materials; Optical properties of nanocrystals and nanoparticles

The colloidal stability and core-shell structure of magnetite nanoparticles coated with alginate by X.Q. Xu; H. Shen; J.R. Xu; M.Q. Xie; X.J. Li (pp. 2158-2164).

The adsorption of alginate (Alg) onto the surface of in water dispersed Fe₃O₄ nanoparticles and zeta potential of alginate-coated Fe₃O₄ nanoparticles have been investigated to optimize the colloidal stability of Alg-coated Fe₃O₄ nanoparticles. The adsorption amount of Alg increased with the decrease of adsorption pH. The zeta potential of Fe₃O₄ nanoparticles shifted to a lower value after adsorption of Alg. The lower adsorption pH was the lower zeta potential of Fe₃O₄ nanoparticles became. The Alg-coated Fe₃O₄ nanoparticles were found to be stabilized by steric and electrostatic repulsions. Those prepared at pH 6 were not stable around pH 5, and those prepared at pH 4 became unstable at pH below 3.5. Alg of M_w 45kDa was a little bit more adsorbed onto nanoparticles surface than that of M_w 24kDa. An average Fe₃O₄ core size of 9.3±1.7nm was found by transmission electronic microscopy. An average hydrodynamic diameter of 30–150nm was measured by photon correlation spectroscopy. However, an average core size of 10nm and an average hydrodynamic diameter of 38nm were estimated from the magnetization curve of the concentrated magnetic fluids (MFs). The maximum available saturation magnetization of MFs was about 3.5kA/m.

Keywords: PACS; 68.45D; 75.50.MMagnetite nanoparticles; Alginate; Adsorption; Zeta potential; Stability; Structure

Ultra-precision machining induced phase decomposition at surface of Zn–Al based alloy by S. To; Y.H. Zhu; W.B. Lee (pp. 2165-2170).

The microstructural changes and phase transformation of an ultra-precision machined Zn–Al based alloy were examined using X-ray diffraction and back-scattered electron microscopy techniques. Decomposition of the Zn-rich η phase and the related changes in crystal orientation was detected at the surface of the ultra-precision machined alloy specimen. The effects of the machining parameters, such as cutting speed and depth of cut, on the phase decomposition were discussed in comparison with the tensile and rolling induced microstrucutural changes and phase decomposition.

Keywords: Ultra-precision machining; Phase decomposition; Tensile deformation; Zn–Al alloys

Phase transformation of Ni–B, Ni–P diffusion barrier deposited electrolessly on Cu interconnect by Jae Woong Choi; Gil Ho Hwang; Won Kyu Han; Sung Goon Kang (pp. 2171-2178).

In this paper, we report that the phase transformation of Ni–B, Ni–P diffusion barriers deposited electrolessly on Cu, for the reason that the Ni–P layer is a more effective diffusion barrier than the Ni–B layer. The Ni₃B crystallized was decomposed to Ni and B₂O₃ above 400°C and the Ni₃P crystallized was decomposed to Ni and P₂O₅ above 600°C respectively in Ar atmosphere. Also, the Ni₃B was decomposed to Ni and free B above 400°C and the Ni₃P was decomposed to Ni and free P above 600°C respectively in H₂ atmosphere. The decomposed Ni formed a solid solution with Cu. The Cu diffusion occurred above 400°C for Ni–B layer and above 600°C for Ni–P layer, respectively. Because the decomposition temperature of Ni–P layer is about 200°C higher than that of Ni–B layer, the Ni–P layer is a more effective barrier for Cu than the Ni–B layer.

Keywords: Ni–B; Ni–P; Cu interconnect; Diffusion barrier; Ni; ₃; B and Ni; ₃; P decomposition

High resolution laser beam induced current focusing for photoactive surface characterization by C. Fernández-Lorenzo; J.A. Poce-Fatou; R. Alcántara; J. Navas; J. Martín (pp. 2179-2188).

The micro-characterization of several surface properties of the solar cells can be accomplished using high-resolution laser beam induced current images. For obtaining these images, a very precise laser beam focusing on the photoactive surface is required. For this purpose, a methodology for obtaining the best focalization associated to the maximum of a peak curve has been developed. In this paper, a data set, obtained from the inner photoconversion properties of the system, has been evaluated with three different numerical analysis techniques: (a) derivative, (b) length and (c) Fourier Transform, in order to get the finest possible peak distribution. Then, an amount of 13 analytical peak curves using the Levenberg Marquardt algorithm to find the best curve that adjusts the data distribution have been analyzed.

Keywords: PACS; 71.20.Mq; 85.30.De; 71.55.CnLBIC; Focusing technique; Solar cell; Photoconversion properties

ZrO₂-reinforced Ni–P plate: An effective catalytic surface for hydrogen evolution by S.M.A. Shibli; V.S. Dilimon; T. Deepthi (pp. 2189-2195).

Nickel and its alloys have recently been emerged as potential catalytic electrode materials for hydrogen evolution reaction in alkaline media. The present work contemplates reinforcement of electroless Ni–P plate with ZrO₂. The plate showed very high stability and excellent electrocatalytic activity. In situ incorporation of ZrO₂ resulted in increase in the rate of deposition of Ni on steel substrate. There was high activation during the initial stage of the plating also. The electrocatalytic activity of the ZrO₂-reinforced Ni electroless plate was found to be highly reproducible and long lasting when used for hydrogen evolution reaction.

Keywords: Nickel electrode; Hydrogen production; Electrocatalysis; Electroless nickel plating; Zirconium oxide-reinforcement

A cast seed-mediated growth method for preparing gold nanoparticle-attached indium tin oxide surfaces by Akrajas Ali Umar; Munetaka Oyama (pp. 2196-2202).

An effective approach to attach gold nanoparticles (AuNPs) directly on indium tin oxide (ITO) surface with higher density is reported. The attachment was carried out using a cast seed-mediated growth method, which was revised from our previous seed-mediated growth approach. The cast seeding with three-cycles of the drop of the seed solution containing Au nano-seed particles and the evaporation at 30°C followed by the treatment in the growth solution containing HAuCl₄, cetyltrimethylammonium bromide (CTAB) and ascorbic acid was found to be suitable to prepare the AuNPs attached ITO surfaces having higher density and narrower size distribution. The 10-cycles cast seeding formed the connected or networked nanostructures of AuNPs, though the optical properties were different from those of the dispersed AuNP-attached ITO. The present cast seeding approach provides a facile and useful strategy to attach AuNPs on the surface without the use of certain organic binder molecules.

Keywords: Gold nanoparticles; Seed-mediated growth method; Cast seeding; Surface modification; Nano-structured material

Microstructure and electrical properties of (Zr, Sn)TiO₄ thin film deposited on Si(100) using a sol–gel process by Ru-Yuan Yang; Yan-Kuin Su; Min-Hang Weng; Yung-Shou Ho (pp. 2203-2207).

Polycrystalline zirconium tin titanate (Zr_0.8Sn_0.2TiO₄, ZST) thin films with thickness of 81nm were deposited successfully along the (100) on a p-type Si substrate by an improved sol–gel method. The deposited films were crystallized when annealing temperature was up to 450°C. The thickness and compositions of the interface layer between the ZST films and Si substrate were identified by high-resolution transmission electron microscope (HRTEM). The electrical properties such as leakage current density, flat-band voltage and capacitance of the films were measured and discussed. Furthermore, the mechanism of the leakage current was also investigated.

Keywords: Microstructure; Electrical properties; (Zr, Sn)TiO; ₄; Sol–gel; Thin film

1064-nm laser fragmentation of thin Au and Ag flakes in acetone for highly productive pathway to stable metal nanoparticles by Mitsuo Kawasaki; Naoya Nishimura (pp. 2208-2216).

The laser-induced fragmentation of thin Au and Ag flakes in acetone by 1064-nm nanosecond laser (with the fluence typically ∼2J/cm²) potentially offers a highly productive pathway to stable metal nanoparticles in liquid. Acetone serves as a superior liquid medium that keeps fine metal nanoparticles free from precipitation even in such concentrated nanoparticle solutions exceeding ∼0.1M. Thin metal flakes have good capability to absorb the 1064-nm laser energy as efficiently as in the visible region. A part of the thus laser-heated molten flakes explosively split into submicroparticles, and some other significant part directly into fine nanoparticles. Both kinds of product particles have minor absorption cross-sections for subsequent laser pulses at 1064nm, and thus no longer fragment further. One of the two kinds of Ag flakes studied in this work yielded fine Ag nanoparticles at a remarkable high production rate of 1.1mg/min for the input laser power of only ∼0.65W.

Keywords: PACS; 61.46.Df; 79.20.Ds; 81.05.Bx; 82.70.DdThin metal flakes; Laser-induced fragmentation; Metal nanoparticles

Room temperature synthesis of water repellent silica coatings by the dip coat technique by Sharad D. Bhagat; Yong-Ha Kim; Young-Soo Ahn (pp. 2217-2221).

The present paper describes the room temperature synthesis of dip coated water repellent silica coatings onto stainless steel substrates using 1,1,1,3,3,3-hexamethyldisilazane as a surface modifying agent. The hydrophobic property of the silica coating was enhanced by increasing its surface roughness, which was achieved by a proper control over the MeOH/TMOS molar ratio ( S) during the synthesis. The contact angle of a water droplet (10μl) increased from 72° to 145° with an increase in the S value from 9.1 to 36.4. The silica coating showed a minimum sliding angle of 15° for a water droplet of 10μl. The water repellent silica coatings are thermally stable up to a temperature of 340°C. The results have been discussed by taking into consideration the contact angle measurements, surface morphology and sol–gel parameters.

Keywords: Water repellency; Sol–gel; Contact angle; AFM; FTIR; TGA–DTA

The effect of plating on magnetron sputtering: Residual stress and scratch behavior of Au/NiCr/Ta multi-layers by Wu Tang; Xiaolong Weng; Longjiang Deng; Kewei Xu (pp. 2222-2225).

Au/NiCr/Ta multi-layers were deposited on Al₂O₃ substrate by magnetron sputtering and plating. The effect of plating technique on magnetron sputtering film in residual stress, crystal orientation and scratch resistance behavior was investigated. The all magnetron sputtering and plating films were highly textured with dominant Au-(111) orientation or a mixture of Au-(111) and Au-(200) orientation and the (111)/(200) intensity ratio were increased after plating. The residual stress in magnetron sputtering films at different substrate temperature was tensile stress with 155–400MPa and it decreased approximately to 50MPa after plating. The scratch resistance could be affected by the film thickness, and it increased approximately linearly with the increase of the thickness of metallic films after plating.

Keywords: Residual stress; Plating; Magnetron sputtering

Photoluminescence study of ZnO nano-islands by Xin Zhou; Shulin Gu; Zhe Wu; Shunmin Zhu; Jiandong Ye; Songming Liu; Rong Zhang; Yi Shi; Youdou Zheng (pp. 2226-2229).

ZnO nano-islands, with much more uniform size, have been grown through two-step method by metal organic chemical vapor deposition (MOCVD). The room temperature band-edge UV emission intensity of nano-islands was usually undetectable or much smaller than that of thin film. Photoluminescence (PL) emission of those nano-islands shows the high intensity nearly as that of ZnO thin film, which is great different from previous reports. By meaningfully analyzing both PL and growth condition of those three samples (bulk ZnO wafer, nano-islands and film), neutral-donor-bound-exciton (D⁰X) emission observed on ZnO nano-islands sample is eventually attributed to hydrogen and aluminum, respectively. The abnormal phenomenon of nano-islands PL intensity has been explained by the point of zinc vacancies ( V_Zn) complex defects. It is considered to govern the nonradiative combination and lead enhanced intensity of UV emission in ZnO nano-islands.

Keywords: PACS; 7855 0779ZnO; Nano-islands; MOCVD

On the incubation effect on two thermoplastics when irradiated with ultrashort laser pulses: Broadening effects when machining microchannels by David Gómez; Igor Goenaga (pp. 2230-2236).

In the present work, the incubation effect on polycarbonate (PC) and poly(methyl methacrylate) (PMMA) foils has been investigated when irradiated with femtosecond pulses (400nm in wavelength, 90fs in pulse length and 1kHz in pulse repetition rate). First, craters produced with different number of pulses ( N=1, 50, 100, 200 and 500) have been obtained and crater diameters measured by means of atomic force microscopy for single-shot craters ( N=1) and confocal optical microscopy for multi-shot craters. Taking into account the gaussian shape of the laser beam, the dependence of crater diameter with fluence has been well established according to a conventional description and, then, fluence thresholds extracted as function of the number of pulses. These values show a good agreement with the incubation model and the incubation coefficient, ξ, has been obtained for both materials ( ξ=0.68 for polycarbonate and ξ=0.61 for poly(methyl methacrylate)). This result supports well the observed fact that the incubation effects play a more important role in some thermoplastics than in any other kind of material, where ξ usually lies between 0.8 and 0.95. In the second part of this work, these results have been considered in the machining of microchannels, since the number of pulses is directly connected to the relative motion of laser beam and the sample through the feedrate of the stages. So, the observed broadening of microchannels with feedrate for a given fluence can be successfully explained and widths predicted with an uncertainty below 2μm. Finally, the channel depth is investigated and the well known transition between a gentle and a strong phase behaviour is showed in the case of polycarbonate.

Keywords: PACS; 79.20.Ds; 06.60.JnFemtosecond phenomena; Laser ablation; Micromachining

Friction and wear behaviour of cp Ti and Ti6Al4V following nitric acid passivation by M. Masmoudi; M. Assoul; M. Wery; R. Abdelhedi; F. El Halouani; G. Monteil (pp. 2237-2243).

Nitric acid passivation increases the thickness of the TiO₂ passive film formed at the cp Ti and Ti6Al4V surface. The TiO₂ oxide, which has a lubricating nature, reduces the wear rate. A linear ball-on-disc friction test has been carried out at room temperature in ambient air, NaCl 3% and Ringer's solutions, with a sliding velocity of 4mms⁻¹ and a normal load of 1N. Friction coefficient curves obtained from ball-on-disc wear test, as well as following the optical microscopy observation of ball trace, indicated the presence of periodic phenomenon. One period can be divided into four stages. This can be clearly seen for cp Ti (accommodation stage, creation of wear particles, adherence of particles layer on the alumina ball and ejection of this layer). In order to confirm this observation and understand the chemical interfacial phenomena, open circuit potential (OCP) measurements were carried out in the same time of friction tests.

Keywords: Titanium; Nitric acid passivation; Friction and wear; Corrosion

Surface segregation in HAYNES 230 alloy by D. Pop; K. Wolski (pp. 2244-2250).

The surface segregation in the Ni-based alloy HAYNES 230 was studied by Auger Electron Spectroscopy and X-ray Photoelectron Spectroscopy between 400 and 1100°C. The qualitative variations of the surface contents of S, P, W, Mo, N, Si, and Mn were determined as a function of annealing temperature and time. It was found that at 925°C the maximum coverage of sulphur at the alloy surface is in the range 0.06–0.15 monolayers. Chromium evaporation from the HAYNES 230 surface under UHV conditions is clearly evidenced for annealing at 1100°C.

Keywords: PACS; 68.35Dv; 81.05Bx; 82.80PvHTR; High temperature reactor; Ni-based alloys; Inconel 617; HAYNES 230; AES; XPS; High-temperature corrosion; Surface segregation; Site competition

Electrodeposition of amorphous Ni–P coatings onto Nd–Fe–B permanent magnet substrates by C.B Ma; F.H Cao; Z. Zhang; J.Q Zhang (pp. 2251-2256).

Decorative and protective Ni–P amorphous coatings were electroplated onto NdFeB permanent magnet from an ortho-phosphorous acid contained bath. The influences of the main electroplating technological parameters including current density, bath pH, bath temperature and H₃PO₃ on the structure and chemical composition of Ni–P coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in conjunction with X-ray diffraction (XRD), scanning transmission electron microscopy (SEM) and X-ray energy-dispersive spectrometry (EDX). The optimized amorphous Ni–P coated NdFeB can stand for ca. 180h against neutral 3.0wt.% NaCl salt spray without any pitting corrosion. Meanwhile, the results also showed that large phosphorous content is the precondition for Ni–P coatings to possess the amorphous structure, but too much high phosphorous content can damage the amorphous structure due to the separation of superfluous P from Ni₂P/Ni₃P and the resultant formation of multi-phase coatings (such as Ni₂P–P).

Keywords: Nd–Fe–B; Amorphous Ni–P electrodeposition; Potentiodynamic polarization; EIS

Synthesis and characterization of the Pd/InVO₄–TiO₂ co-doped thin films with visible light photocatalytic activities by Lei Ge; Mingxia Xu; Haibo Fang (pp. 2257-2263).

Novel Pd/InVO₄–TiO₂ thin films with visible light photocatalytic activity were synthesized from the Pd and InVO₂ co-doped TiO₂ sol via sol–gel method. The photocatalytic activities of Pd/InVO₄–TiO₂ thin films were investigated based on the oxidative decomposition of methyl orange in aqueous solution. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV–vis absorption spectroscopy (UV–vis). The results indicate that the Pd/InVO₄–TiO₂ thin films are compact, uniform and consist of sphere nanoparticles with diameters about 80–100nm. The UV–vis spectra show that the Pd/InVO₄–TiO₂ thin films extend the light absorption spectrum toward the visible region. XPS results reveal that doped Pd exist in the form of metallic palladium. The photocatalytic experiments demonstrate that Pd doping can effectively enhance the photocatalytic activities of InVO₄–TiO₂ thin films in decomposition of aqueous methyl orange under visible light irradiation. It has been confirmed that Pd/InVO₄–TiO₂ thin films could be excited by visible light ( E<3.2eV) due to the existence of the Pd and InVO₄ doped in the films.

Keywords: Visible light; Doping; Pd/InVO; ₄; –TiO; ₂; Thin films; Photocatalysis

Photoconductive ultraviolet detectors based on ZnO films by X.G. Zheng; Q.Sh. Li; J.P. Zhao; D. Chen; B. Zhao; Y.J. Yang; L.Ch. Zhang (pp. 2264-2267).

Properties of photoconductive ultraviolet detectors fabricated on ZnO films were presented. Highly c-axis oriented ZnO films were grown on glass substrates by pulsed laser deposition. Ultraviolet photodetectors were fabricated based on metal–semiconductor–metal planar structures. The photoresponsivity and the quantum efficiency are much higher in the ultraviolet range than in the visible range, and the peak values are around 360nm. Photocurrent transients show that the detector has a large photocurrent with the peak value of 2.8mA, and a slow photoresponse with a rise time of 5min and a decay time of 7min. The response curve of the detector is fitted well with exponential curve. The large photocurrent should result from the both effects of the accumulation of conduction electrons and the decrease of the barrier height between crystallites. The relaxation time constant τ obtained from the curve fitting represents the time accumulation during the process. The neutralization of photogenerated holes by negatively charged oxygen ions plays a key role in the photoconductive characteristics of ZnO polycrystalline films.

Keywords: Pulsed laser deposition; ZnO; Photodetector

Growth of highly-oriented CaCu₃Ti₄O₁₂ thin films on SrTiO₃ (100) substrates by a chemical solution route by Lixin Feng; Youwen Wang; Yueyue Yan; Guanghan Cao; Zhengkuan Jiao (pp. 2268-2271).

Highly-oriented CaCu₃Ti₄O₁₂ (CCTO) thin films deposited directly on SrTiO₃ (100) substrates have been developed successfully using a chemical solution coating method. X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were employed to characterize the structure and the morphology. It was observed that the CCTO thin films had the 1μm×1μm domain-like microstructure that consists of compact grains of about 0.1μm in size. The cross sectional SEM image shows that the CCTO grains grow regularly close to the clear interface between the CCTO film and the SrTiO₃ substrate. The result was discussed in terms of lattice mismatch between CCTO and SrTiO₃.

Keywords: PACS; 77.55+f; 68.55−a; 81.20.FwSol–gel preparation; Thin films; CaCu; ₃; Ti; ₄; O; ₁₂; perovskite; Electron microscopy

Influence of preheating and hematite content of clay brick pavers on the characteristics of lines marked with a Nd:YAG laser by J.W. Restrepo; J.M. Fernández-Pradas; M.A. Gómez; P. Serra; J.L. Morenza (pp. 2272-2277).

This paper reports the clay brick pavers marking by vitrification with a continuous wave Nd:YAG laser (1064nm). The influence of a preheating and the chemical composition of the bricks on the morphological, visual and dimensional characteristics was studied. The lines marked at room temperature resulted in a discontinuous green glassy phase due to the presence of defects. A remarkable reduction of the defect amount, resulting in smooth, gleaming and darker lines, was obtained when preheating the bricks at 350°C. The green tone, width, depth and cross-section area of the lines depend on the bricks’ chemical composition and thermal condition, as well as, on the laser energy density. Thus, decorative patterns of good visual quality can be marked by laser vitrification on clay brick pavers preheated at 350°C.

Keywords: PACS; 61.80.Ba; 42.62.-b; 81.05.Je; 81.05.KfLaser marking; Clay brick pavers; Vitrification; Bubbles; Cracks

Microwave absorption properties of composite powders with low density by Guohong Mu; Haigen Shen; Jianxun Qiu; Mingyuan Gu (pp. 2278-2281).

The composites of barium ferrite coated on hollow ceramic microspheres were prepared using sol–gel technique. The crystal structure, morphology and microwave absorption properties of composite powders with different weight ratio of microspheres were studied with XRD, EDS, FESEM and vector network analyzer. The results show that the microwave absorption properties of composite powders are greatly improved. The maximum microwave loss of composite powders reaches 31dB with an amount of 50wt.% microspheres, and its density is only about 1.80g/cm³. The effect of hollow ceramic microspheres on the microwave absorption property is also discussed.

Keywords: Microwave absorption; Hollow ceramic microsphere; Barium ferrite; Sol–gel

Phosphonate electrochemical recognition by molecularly imprinted deposited film by Chenghang Wang; Chunya Li; Fang Wang; Changfa Wang (pp. 2282-2288).

In this paper, thin films of titanium oxide imprinted with O, O-dimethyl-(2,4-dichlorophenoxyacetoxyl)(3′-nitrobenyl) methinephosphonate (Phi-NO₂) were prepared via liquid phase deposition (LPD) method on a glassy carbon electrode. The imprinted molecular in the films was removed by treatment with immersion in CH₂Cl₂. X-ray diffraction (XRD) and electrochemical methods were introduced to show the evidence of the molecular imprinting phenomenon. It was also found that the recognition ability of the sensor depended on the substituents associated with tridimensional structures of the nitro-compounds. Under the optimized condition, the sensor showed better sensitivity, selectivity and reproducibility to the imprinted molecule and the linear relationship between the current and the concentration of analyte in the range of 0.1–50μM was obtained. LPD proved to be a powerful method for imprinting titanium oxide thin sense films.

Keywords: TiO; ₂; thin film; Molecularly imprinted sensor; Liquid phase deposition; Phosphonate

Cathodic deposition of CdSe films from dimethyl formamide solution at optimized temperature by J. Datta; C. Bhattacharya; S. Bandyopadhyay (pp. 2289-2295).

In the present paper, thin film CdSe compound semiconductors have been electroplated on transparent conducting oxide coated glass substrates from nonaqueous dimethyl formamide bath containing CdCl₂, KI and Se under controlled temperature ranging from 100 to 140°C. Thickness of the deposited films as obtained through focussed ion beam technique as well as their microstructural and photoelectrochemical properties have been found to depend on temperature. The film growth was therefore optimized at a bath temperature ∼125°C. The formation of crystallites in the range of 100–150nm size has been ascertained through atomic force microscopy and scanning electron microscopy. Energy dispersive analysis of X-rays for the as deposited film confirmed the 1:1 composition of CdSe compound in the matrix exhibiting band-gap energy of 1.74eV. Microstructural properties of the deposited films have been determined through X-ray diffraction studies, high-resolution transmission electron microscopy and electron diffraction pattern analysis. Electrochemical impedance spectroscopy and current-potential measurements have been performed to characterize the electrochemical behavior of the semiconductor–electrolyte interface. The photo-activity of the films have been recorded in polysulphide solution under illumination and solar conversion efficiency ≥1% was achieved.

Keywords: PACS; 84.60.Dn; 81.05.E; 81.15.Pq; 61.16.B; 73.40.MSemiconductors; Liquid-junction solar cells; Electrodeposition; Activation energy; Electron microscopy; Electrochemical properties

Nature and thermal stability of adsorbed intermediates formed during the reaction of diesel soot with nitrogen dioxide by B. Azambre; S. Collura; J.M. Trichard; J.V. Weber (pp. 2296-2303).

The reactivity of a diesel exhaust soot sample towards 1000ppm NO₂/balance Ar was investigated at moderate temperature using thermogravimetric analysis (TGA), temperature-programmed desorption (TPD-MS) and diffuse reflectance infrared spectroscopy (DRIFTS) with the aim to evidence the nature and thermal stability of adsorbed intermediates formed during the reaction. In the range 25–200°C, the reaction pathways are influenced by the temperature dependency of the reaction regimes. While weak adsorption of NO₂ prevails at temperatures under ca. 60°C, it is found that associative and dissociative chemisorption occurs on the whole range of temperatures investigated, creating, respectively, nitrogenated (RNO_x) and oxygenated (RO_x) adsorbed intermediates on soot surface. DRIFTS and TPD experiments reveal that major surface species include on the one hand alkyl-nitrite and -nitrate esters adopting presumably a chelated or bidentate configuration on soot surface and on the other hand more stable acidic oxygenated surface complexes formed by reduction of NO₂.

Keywords: Diesel soot; Reactivity; NO; ₂; adsorption; TPD; DRIFTS; TGA

A novel waterborne polyurethane containing short fluoroalkyl chains: Synthesis, characterization and its application on cotton fabrics surface by Wan-Chao Jiang; Yangen Huang; Guo-Tuan Gu; Wei-Dong Meng; Feng-Ling Qing (pp. 2304-2309).

A novel waterborne polyurethane containing short fluoroalkyl groups (–CF₃) was designed and synthesized. It was applied as a surface modification agent on cotton fabrics. The treated fabrics showed very good hydrophobicity and the contact angles for water reached 147°. In addition, it also showed good washing durability, the contact angle still reached 130° even after 30 washing cycles, and the water uptake was 1 order of magnitude less than that of the untreated cotton fabrics.

Keywords: PACS; 82.65Waterborne polyurethane; Short fluoroalkyl side chains; Hydrophobicity; Cotton fabrics

Human serum albumin (HSA) adsorption onto a-SiC:H thin films deposited by hot wire chemical vapor deposition by Bibhu P. Swain (pp. 2310-2314).

In the present paper, we report the study of the adsorption behavior of human serum albumin (HSA) onto surfaces of a-SiC:H thin films deposited by using the hot wire chemical vapor deposition (HWCVD) technique. The surface composition and surface energy of the various substrates as well as the evaluation of the adsorbed amount of protein has been carried out by means of X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FTIR) spectroscopy, AFM and contact angle measurements. At the immediate effect of HSA interaction with a-SiC:H films N is adsorbed on the surface and stabilized after 3 days. Preliminary observation found that Si and O atom are desorbed from the surface while C and N set adsorbed to the surface of the a-SiC:H film.

Keywords: HWCVD; FTIR; XPS; AFM; Contact angle

ZrB₂ Schottky diode contacts on n-GaN by R. Khanna; K. Ramani; V. Cracium; R. Singh; S.J. Pearton; F. Ren; I.I. Kravchenko (pp. 2315-2319).

The annealing temperature dependence of rectifying contact characteristics on epilayers of n-GaN using a ZrB₂/Ti/Au metallization scheme deposited by sputtering are reported. A maximum barrier height of 0.57eV was achieved on samples annealed at 200°C, with the reverse breakdown voltage of the diodes also a maximum after this anneal. The barrier height was essentially independent of annealing temperature up to 700°C even though Auger electron spectroscopy depth profiling showed the onset of inter-contact metallurgical reactions at 500°C. The Ti began to outdiffuse to the surface at temperatures of 350°C, while the ZrB₂/GaN interface showed no evidence of reaction even at 800°C. The reverse current magnitude of diodes fabricated using the ZrB₂ contacts was larger than predicted by thermionic emission alone.

Keywords: GaN; Schottky; Contacts

Scratch resistance anisotropy in biaxially oriented polypropylene and poly(ethylene terephthalate) films by H.-Y. Nie; M.J. Walzak; N.S. McIntyre (pp. 2320-2326).

Using a diamond-tipped stylus, scratch tests were conducted on biaxially oriented polypropylene and poly(ethylene terephthalate) films in the two draw directions, i.e., the machine-direction (MD) and the transverse-direction (TD) along which the draw ratios are different. Atomic force microscopy study of those scratches revealed a significant anisotropy in the scratch resistance between the MD and TD for both of the polymer films. We confirmed that the scratch resistance of polymer strands is closely related to the draw ratios, which determine the mechanical strength and optical clarity of biaxially oriented polymer films.

Keywords: PACS; 62.20.Fe; 68.37.Tj; 68.47.MnBiaxially oriented polymer film; BOPP; PET; Draw ratio; Scratch resistance anisotropy

Theoretical analysis for the heterogeneous decomposition of hydrogen sulfide to hydrogen on an iron-metallic plate in a laminar stagnation-point flow by J.C. Martínez; F. Méndez; C. Treviño (pp. 2327-2335).

In this work, we have theoretically analyzed the conversion process of hydrogen sulfide, H₂S, to atomic hydrogen, H⁰, in a planar stagnation-point flow over an iron-metallic surface. We assume that a binary mixture of hydrogen sulfide and methane composes the laminar stagnation flow. In order to characterize this complex phenomenon with very specific chemical activities on the surface of the metallic plate, we propose a heterogeneous reaction scheme based on four reactions: two electrochemical, one adsorption and an additional exothermic reaction needed to complete the direct conversion of hydrogen sulfide to hydrogen on the surface of the iron. The nondimensional governing equations, which include the mass species and momentum conservation of the mixture and the molecular diffusion of hydrogen into the iron plate, are numerically solved by conventional finite-difference methods. The numerical results show the critical conditions of the H₂S decomposition as functions of the involved nondimensional parameters of the present model. In particular, we show parametrically the influence that has the initial concentration of H₂S on the surface coverage of the chemical products HS⁻ H⁺ and H⁰ derived from the chemical and electrochemical reactions.

Keywords: PACS; 82.30.Lp; 82.40.-gHydrogen sulfide; Stagnation flow; Heterogeneous reactions; Iron plate; Hydrogen diffusion

The growth of thin fluorescein films on Ag (110) by H.Q. Qian; H.Y. Mao; Q. Chen; F. Song; Y.W. Hu; H. Huang; H.J. Zhang; H.Y. Li; P.M. He; S.N. Bao (pp. 2336-2339).

The thin fluorescein films grown on Ag (110) have been studied by the ultraviolet photoemission spectroscopy (UPS). Four emission features are located at 2.7, 3.8, 7.4 and 9.8eV below the Fermi level, respectively. The angle-resolved ultraviolet photoemission spectroscopy (ARUPS) measurements show that the Triring plane of fluorescein is nearly parallel to the substrate and the axis of CO is close to the[11¯0] azimuth.

Keywords: PACS; 68.55.Jk; 73.20.At; 82.65.+rOrganic semiconductor material; Ultraviolet photoemission spectroscopy

Stability of Ti/Al/ZrB₂/Ti/Au ohmic contacts on n-GaN by R. Khanna; S.J. Pearton; F. Ren; I.I. Kravchenko (pp. 2340-2344).

Ohmic contacts on n-GaN using a novel Ti/Al/ZrB₂/Ti/Au metallization scheme were studied using contact resistance, scanning electron microscopy and Auger electron spectroscopy (AES) measurements. A minimum specific contact resistivity of 3×10⁻⁶Ωcm² was achieved at an annealing temperature of 700°C. The lowest contact resistance was obtained for 60s anneals. The contact resistance was essentially independent of measurement temperature, indicating that field emission plays a dominant role in the current transport. The Ti and Al in the contact stack began to outdiffuse to the surface at temperatures of ∼500°C, while at 1000°C the B also began to migrate to the surface. By this latter temperature, AES showed almost complete intermixing of the metallization even though the contact morphology was still smooth. The boride appears susceptible to getting of residual water vapor during sputter deposition.

Keywords: GaN; Ohmic contacts

Fabrication of p-type ZnMgO codoped with Al and N using dc reactive magnetron sputtering by Y.M. Ye; Z.Z. Ye; L.L. Chen; B.H. Zhao; L.P. Zhu (pp. 2345-2347).

We report the fabrication of p-type Zn_0.9Mg_0.1O thin films codoped with Al and N via dc magnetron sputtering method. The XRD patterns show the as-grown films with a strict c-axis orientation. Hall effect measurement confirms the conversion of conduction type in a certain range of temperature. The obtained films with the best electrical properties show a hole concentration in the order of 10¹⁸cm⁻³ and resistivity in the range of 20–30Ωcm. The transmittance spectrum reveals a distinct blue shift between pure ZnO and Al–N codoped Zn_0.9Mg_0.1O films, which confirms the effective incorporation of Mg. The band gap of the alloy is controllable.

Keywords: PACS; 61.72.V; 72.80.E; 73.61.G; 81.05.Dp-Type conduction; Doping; dc reactive magnetron sputtering; ZnMgO; Semiconducting II–VI materials

The formation of supported monodisperse Au nanoparticles by UV/ozone oxidation process by M.C. Plante; J. Garrett; S.C. Ghosh; P. Kruse; H. Schriemer; T. Hall; R.R. LaPierre (pp. 2348-2354).

The influence of surface preparation of GaAs (100)- and (111)B-oriented substrates on the self-assembly of Au nanoparticles has been investigated. It has been shown that an UV/ozone surface oxidation process, applied prior to the deposition of a thin Au film, enables the formation of well-distributed Au particles that are very uniform in size. Particles of 4.5±1.4nm diameter have been obtained by the appropriate heat treatment of a 1-nm-thick Au film. The general applicability of this approach has been demonstrated by reproducing the results on a Si (111) substrate. The process therefore yielded comparable results independent of the surface orientation. Possible operative mechanisms are discussed including Ostwald ripening, particle migration and coalescence, and Coulomb repulsion of the Au deposition.

Keywords: PACS; 61.46.-w; 61.46.Bc; 61.46.Df; 68.08.Bc; 68.37.-d; 68.47.Gh; 68.47.Jn; 68.60.Dv; 81.16.Dn; 81.65.MqGold nanoparticles; Self-assembly; Oxidation processes; Gallium arsenide; UV/ozone

Erratum to “Formation of photoresist-free patterned ZnO film containing nano-sized Ag by photochemical solution deposition�? [Appl. Surf. Sci. 252 (2006) 7739–7742] by Chae-Seon Hong; Hyeong-Ho Park; Seok-Joo Wang; Jooho Moon; Hyung-Ho Park; Ross H. Hill (pp. 2355-2355).

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Applied Surface Science (v.253, #4)