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Applied Surface Science (v.255, #8)

The photoemission study of NdNiO₃/NdGaO₃ thin films, through the metal–insulator transition by K. Galicka; J. Szade; P. Ruello; P. Laffez; A. Ratuszna (pp. 4355-4361).

The electronic structure of thin films NdNiO₃/NdGaO₃ with various thicknesses (from 17nm to 150nm), have been studied by photoemission spectroscopy at 300K and 169K. The XPS results are consistent with the literature ab initio calculations of the NdNiO₃ electronic structure. A noticeable variation attributed to the metal–insulator (MI) transition has been found only for the films with relatively high thickness (150nm). Furthermore, the photoemission spectra and their temperature dependence have been discussed with regard to the results of dc electrical resistivity measurements which also exhibit large thickness dependence. Finally, these new results support a possible large hetero-epitaxial effect on the thinnest sample (17nm) which could stress the NdNiO₃ structure and consequently makes its electronic structure nearly stabilized.

Keywords: Photoemission; NdNiO; ₃; /NdGaO; ₃; thin films; Metal–insulator transition

Porosity and effective mechanical properties of plasma-sprayed Ni-based alloy coatings by X.C. Zhang; B.S. Xu; F.Z. Xuan; S.T. Tu; H.D. Wang; Y.X. Wu (pp. 4362-4371).

The aim of this paper was to address the relationship between the porosity and micro-mechanical properties of the Ni-based alloy coatings which were prepared by a novel plasma-spraying system. The porosity and the mechanical properties of the coatings varied through changing the spraying parameters. Experimental results showed that the measured data of porosity, Young’s modulus and micro-hardness of the coating exhibited high scattering and followed the Weibull distribution. From statistic trend, the micro-hardness and Young’s modulus of the coating decreased with increasing the porosity of the coating. Moreover, generally, with increasing the micro-hardness of the coating, Young’s modulus of the coating increased.

Keywords: Porosity; Coating; Mechanical properties; Statistics; Plasma spraying

Effects of target–substrate geometry and ambient gas pressure on FePt nanoparticles synthesized by pulsed laser deposition by J.J. Lin; L.S. Loh; P. Lee; T.L. Tan; S.V. Springham; R.S. Rawat (pp. 4372-4377).

FePt nanoparticles, in the forms of nanoparticle agglomerates and floccules-like nanoparticle networks, can be synthesized by pulsed laser deposition (PLD) at different ambient gas pressures. Backward plume deposition (BPD), as special target–substrate geometry, can achieve higher uniformity in terms of agglomerate size and size distribution, compared to conventional PLD. Both as-deposited FePt nanoparticles exhibit low K_u fcc phase and post-annealing at 600°C is required for the phase transition to high K_u fct phase. FePt nanoparticle agglomerates deposited by BPD were found to have better fct phase crystallinity after annealing, which may be caused by the higher kinetic energy of backward moving ablated species due to shorter travel distance.

Keywords: FePt; PLD; Backward plume deposition; Nanoparticle; MOKE

Photo-catalytic H₂ evolution over a series of Keggin-structure heteropoly blue sensitized Pt/TiO₂ under visible light irradiation by Ning Fu; Gongxuan Lu (pp. 4378-4383).

We report the visible light-induced hydrogen generation over a series of Keggin-structure heteropoly blue (HPB) anions (PW₁₂O₄₀³⁻, phosphotungstic blue (PTB), GeW₁₂O₄₀⁴⁻ (GTB), SiW₁₂O₄₀⁴⁻ (STB), BW₁₂O₄₀⁵⁻ (BTB)) sensitized Pt/TiO₂ photo-catalysts. The sensitization of TiO₂ by HPB was certified using photo-electrochemical measurements and UV–vis absorption spectra. PTB showed the most pronounced sensitization effect for TiO₂ in those HPB anions and Pt/TiO₂–PTB showed the highest hydrogen generation activity. The sensitization of TiO₂ was significantly dependent on the reduction potential of HPA, which was determined by the kind of central atom in HPA.

Keywords: PACS; 81.07.−bHeteropoly blue (HPB); Visible light; Sensitization; TiO; ₂

Nanohole 3D-size tailoring through polystyrene bead combustion during thin film deposition by Xiaofeng Peng; Itaru Kamiya (pp. 4384-4388).

A novel approach is presented for nanohole 3D-size tailoring. The process starts with a monolayer of polystyrene (PS) beads spun coat on silicon wafer as a template. The holes can be directly prepared through combustion of PS beads by oxygen plasma during metal or oxide thin film deposition. The incoming particles are prevented from adhering on PS beads by H₂O and CO₂ generated from the combustion of the PS beads. The hole depth generally depends on the film thickness. The hole diameter can be tailored by the PS bead size, film deposition rate, and also the combustion speed of the PS beads. In this work, a series of holes with depth of 4–24nm and diameter of 10–36nm has been successfully prepared. The hole wall materials can be selected from metals such as Au or Pt and oxides such as SiO₂ or Al₂O₃. These templates could be suitable for the preparation and characterization of novel nanodevices based on single quantum dots or single molecules, and could be extended to the studies of a wide range of coating materials and substrates with controlled hole depth and diameters.

Keywords: Nanohole; Nanolithography; Polystyrene beads; Colloidal quantum dots; Combustion; Thin film deposition

Invalidating mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process by Wei Wang; Ya-Bing Li; Yong-Lei Li (pp. 4389-4392).

The invalidating process and related mechanism of bis (3-sulfopropyl) disulfide (SPS) during copper via-filling process were investigated by means of electrochemical polarization measurement, and the mass spectrometry (MS) testing was employed to confirm the molecular weight (MW) and the structure of SPS invalidating products. Meanwhile, quantum chemistry calculation was used to verify the rationality of the proposed invalidating course. These results suggest that the solution containing SPS has invalidated after the passed charges (PC) reached 15AhL⁻¹ under electrifying condition. The adsorption ability of SPS decrease gradually with the increase of PC during the invalidating process. The invalidation of SPS is an oxidation process related to the dissolved oxygen in the solution, during which the active functional group –S–S– is oxidized to –SO_x–SO_y–. As a result, the accelerating effect of SPS on copper reduction will gradually diminish.

Keywords: PACS; 84.45.−hVia-filling; Accelerating effect; Adsorption ability; Invalidating course; Invalidating product

Interface characteristics and mechanical properties of short carbon fibers/Al composites with different coatings by Yiping Tang; Lei Liu; Weiwei Li; Bin Shen; Wenbin Hu (pp. 4393-4400).

Three kinds of coatings, Ni, Cu and Al₂O₃, were obtained on the surface of short carbon fibers (SCFs). The interface characteristics and mechanical properties of SCFs/Al composites with the various coatings were systematically studied in this paper. The results showed that, compared to non-coating, Ni or Cu coating improved the wettability of SCFs and Al melt. However, the harmful phases Al₃Ni or CuAl₂ generated in interface zone and Al matrix result in the lower mechanical properties. Al₂O₃ coating protected the SCFs and prevented the harmful reaction of Al and SCFs. The interface of Al/Al₂O₃/SCF without any other phase was clean and well bonded, and the Al₂O₃-coated SCFs/Al composite had the highest mechanical properties. The interfacial indentation and fracture mechanism of all the composites were analyzed in detail.

Keywords: Interface; Property; Aluminium; Short carbon fibers; Composite; Coating

Structural and optical properties of Ga2(1− x₎In2_xO₃ films prepared on α-Al₂O₃ (0001) by MOCVD by Fan Yang; Jin Ma; Caina Luan; Lingyi Kong (pp. 4401-4404).

Ga2(1− x₎In2_xO₃ thin films with different indium content x [In/(Ga+In) atomic ratio] were prepared on α-Al₂O₃ (0001) substrates by the metal organic chemical vapor deposition (MOCVD). The structural and optical properties of the Ga2(1− x₎In2_xO₃ films were investigated in detail. Microstructure analysis revealed that the film deposited with composition x=0.2 was polycrystalline structure and the sample prepared with x up to 0.8 exhibited single crystalline structure of In₂O₃. The optical band gap of the films varied with increasing Ga content from 3.72 to 4.58eV. The average transmittance for the films in the visible range was over 90%.

Keywords: PACS; 61.10.Nz; 68.37.Lp; 81.15.GhGa; 2(1−; x; ₎; In; 2; _x; O; ₃; films; Microstructure; Optical properties; MOCVD

Investigation of the hydrophobic recovery of various polymeric biomaterials after 172nm UV treatment using contact angle, surface free energy and XPS measurements by Claire O’Connell; Richard Sherlock; Michael D. Ball; Balazs Aszalós-Kiss; Una Prendergast; Thomas J. Glynn (pp. 4405-4413).

Surface modification as a route to improving the performance of polymeric biomaterials is an area of much topical interest. Ultraviolet (UV) light treatment has received much attention, but polymers so treated revert to their original surface condition over a period of time—an effect known as hydrophobic recovery. It is important to develop an understanding of the underlying processes contributing to the effect, since it has an impact on the applicability of UV treatment. In this work a number of polymeric biomaterials were surface-modified using 172nm UV light from an excimer lamp. The modified polymers were characterised using contact angle, surface free energy (SFE) measurements and X-Ray Photoelectron Spectroscopy (XPS) techniques. The wettability, variation in surface free energy and chemical functionality changes were analysed on the surfaces immediately after UV treatment and subsequently over a period of 28 days. It was noted that hydrophobic recovery proceeds at a different rate for each polymer, is generally a two-phase process and that surfaces are still more hydrophilic after 28 days than the original untreated state. XPS analysis reveals that particular chemical configurations move from the surface at a faster rate than others which may contribute to the two-phase nature of the process.

Keywords: PACS; 81.40.Cd; 61.80.Ba; 79.60.−i; 68.35.Md172; nm excimer lamp; Polymeric biomaterials; Hydrophobic recovery; Surface free energy; XPS

Photoluminescent properties of silicon carbide and porous silicon carbide after annealing by Ki-Hwan Lee; Seung-Koo Lee; Ki-Seok Jeon (pp. 4414-4420).

Photoluminescent (PL) p-type 6H porous silicon carbides (PSCs), which showed a strong blue-green photoluminescence band centered at approximately 490nm, were annealed in Ar and vacuum conditions. The morphological, optical, and chemical states after annealing are reported on electrochemically etched SiC semiconductors.The thermal treatments in the Ar and vacuum environments showed different trends in the PL spectra of the PSC. In particular, in the case of annealing in a vacuum, the PL spectra showed both a weak red PL peak near 630nm and a relatively intense PL peak at around 430nm in the violet region. SEM images showed that the etched surface had spherical nanostructures, mesostructures, and islands. With increasing annealing temperature it changes all spherical nanostructures. The average pore size observed at the surface of the PSC before annealing was of the order of approximately 10nm.In order to investigate the surface of a series of samples in detail, both the detection of a particular chemical species and the electronic environments at the surface are examined using X-ray photoelectron spectroscopy (XPS). The chemical states from each XPS spectrum depend differently before and after annealing the surface at various temperatures. From these results, the PL spectra could be attributed not only to the quantum size effects but also to the oxide state.

Keywords: Porous silicon carbides; Photoluminescent; Annealing; X-ray photoelectron spectroscopy

Growth and field emission properties of globe-like diamond microcrystalline-aggregate by Jin-hai Gao; Lan Zhang; Limin Zhao; Haoshan Hao (pp. 4421-4424).

The globe-like diamond microcrystalline-aggregates were fabricated by microwave plasma chemical vapor deposition (MPCVD) method. The ceramic with a Ti mental layer was used as substrate. The fabricated diamond was evaluated by Raman scattering spectroscopy, X-ray diffraction spectrum (XRD), and scanning electron microscope (SEM). The field emission properties were tested by using a diode structure in a vacuum. A phosphor-coated indium tin oxide (ITO) anode was used for observing and characterizing the field emission. It was found that the globe-like diamond microcrystalline-aggregates exhibited good electron emission properties. The turn-on field was only 0.55V/μm, and emission current density as high as 11mA/cm² was obtained under an applied field of 2.9V/μm for the first operation. The growth mechanism and field emission properties of the globe-like diamond microcrystalline-aggregates are discussed relating to microstructure and electrical conductivity.

Keywords: Diamond microcrystalline-aggregate; Field emission; Chemical vapor deposition

Structure and mechanical properties of reactive sputtering CrSiN films by Guangan Zhang; Liping Wang; S.C. Wang; Pengxun Yan; Qunji Xue (pp. 4425-4429).

CrSiN films with various Si contents were deposited by reactive magnetron sputtering using the co-deposition of Cr and Si targets in the presence of the reactive gas mixture. Comparative studies on microstructure and mechanical properties between CrN and CrSiN films with various Si contents were carried out. The structure of the CrSiN films was found to change from crystalline to amorphous structure as the Si contents increase. Amorphous phase of Si₃N₄ compound was suggested to exist in the CrSiN film. The growth of films has been observed from continuous columnar structure, granular structure to glassy-like appearance morphology with the increase of silicon content. The film fracture changed from continuous columnar structure, granular structure to glassy-like appearance morphology with the increase of silicon content. Two hardness peaks of the films as function of Si contents have been discussed.

Keywords: PACS; 62.20.−x; 62.20.Qp; 68.35.Gy; 81.40.Pq; 87.15.LaCrSiN films; Magnetron sputtering; Microstructure; Mechanical properties

Photoluminescence investigation of ZnO:P nanoneedle arrays on InP substrate by pulsed laser deposition by D.Q. Yu; L.Z. Hu; J. Li; H. Hu; H.Q. Zhang; J.M. Bian; J.X. Zhu; S.S. Qiao; X. Chen; B. Wang (pp. 4430-4433).

Phosphorus-doped ZnO nanoneedle arrays were prepared by phosphorus diffusion from InP substrate using a pulsed laser deposition (PLD) technique. The optical properties of ZnO nanoneedle were investigated by photoluminescence (PL) spectroscopy. Low-temperature photoluminescence spectrum measurements exhibited five acceptor-related emission peaks. The excitation intensity and temperature dependent photoluminescence spectra confirmed that the emission peaks corresponded to neutral-acceptor bound exciton, free electron to acceptor, donor–acceptor pairs, and their first and second photon replicas transitions. Acceptor-binding energy was determined to be 135–167meV, which agrees well with the best-fitting result of the temperature dependent photoluminescence measurements and is reasonable in terms of theoretic prediction in ZnO.

Keywords: PACS; 81.07.Bc; 81.16.−c; 61.46.HkZnO; Nanoneedle arrays; Photoluminescence; Phosphorus-doped

Evaluation of surface characteristics under fretting of electrical contacts: Removal behaviour of hot dipped tin coating by Young Woo Park; G.N.K. Ramesh Bapu; Kang Yong Lee (pp. 4434-4442).

The fretting corrosion behaviour of hot dipped tin coating is investigated at low fretting cycles at ±25μm displacement amplitude, 0.5N normal load, 3Hz frequency, 45–50% relative humidity, and 25±1°C temperature. The typical characteristics of the change in contact resistance with fretting cycles are explained. The fretted surface is examined using laser scanning microscope, scanning electron microscope and energy dispersive X-ray analysis to assess the surface profile, extent of fretting damage, extent of oxidation and elemental distribution across the contact zone. The interdependence of extent of wear and oxidation increases the complexity of the fretting corrosion behaviour of tin coating. The variation of contact resistance clearly revealed the fretting of tin coating from 50 to 1200 cycles and the fretting of the substrate above 1200 cycles. The observed low and stable contact resistance region and the fluctuating resistance region at various fretting cycles are explained and substantiated with Scanning electron microscopy (SEM), laser scanning microscope (LSM) and energy dispersive analysis of X-rays (EDAX) analysis results of the fretted surface.

Keywords: Fretting corrosion; Contact resistance; Hot dipping; Coating; Surface characterization

Influence of substrate temperature on the texture of barium ferrite film by magnetron sputtering by Zeyu Guo; Wanli Zhang; Hong Ji; Bin Peng; Wenxu Zhang (pp. 4443-4445).

Barium ferrite thin films have been prepared by radio frequency magnetron sputtering on a sapphire (001) substrate at substrate temperature of 500°C and 650°C, respectively. The films were further annealed in air at 1000°C for 5h. X-ray diffraction shows that the films at the lower substrate temperatures have a good epitaxial relation with respect to the substrate, while the samples under the higher substrate temperatures have (109) planes parallel to the substrate. The remanence ratio decreases from 0.82 to 0.47 when the substrate temperature is increased. We attribute the variation of the growth direction to the enhanced vertical mobility of the deposited atoms when the substrate temperature is increased.

Keywords: PACS; 61.10.−i; 68.55.−a; 75.70.AkBarium ferrite; Thin films; Texture

Surface modification of a biomedical polyethylene terephthalate (PET) by air plasma by Liqing Yang; Jierong Chen; Yafei Guo; Zheng Zhang (pp. 4446-4451).

In this work, low-pressure air plasma has been used to improve polyethylene terephthalate (PET) surface properties for technical applications. Surface free energy values have been estimated using contact angle value for different exposure times and different test liquids. Surface composition and morphology of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Surface topography changes related with the etching mechanism have been followed by weight loss study. The results show a considerable improvement in surface wettability and the surface free energy values even for short exposure times in the different discharge areas (discharge area, afterglow area and remote area), as observed by a remarkable decrease in contact angle values. Change of chemical composition made the polymer surfaces to be highly hydrophilic, which mainly depends on the increase in oxygen-containing groups. In addition to, the surface activation and AFM analyses show obvious changes in surface topography as a consequence of the plasma-etching mechanism.

Keywords: Surface modification; X-ray photoelectron spectroscopy (XPS); Contact angle; Atomic force microscopy (AFM); Low-pressure RF plasma; Polyethylene terephthalate film

Quantum rings formed in InAs QDs annealing process by Guo-zhi Jia; Jiang-hong Yao; Yong-chun Shu; Xiao-dong Xing; Biao Pi (pp. 4452-4455).

InAs quantum dots (QDs) were grown by molecular beam epitaxy in the Stranski-Krastanow growth mode. The samples were placed between two undoped GaAs slices and annealed in nitrogen ambient at different temperature. Effect of annealing temperature on the evolution of QDs morphology is investigated by the AFM. This behavior can be attributed to the mechanisms of QDs ripening, intermixing and segregation in the annealing process. A number of QDs have evoluted into the uniform distribution quantum rings (QRs) when the sample was annealed at the temperature of 800°C. The results indicated that high density and uniform QRs can be obtained by the post-growth technique.

Keywords: PACS; 81.05.Ea; 81.07.Ta; 81.16.DnQuantum rings; Molecular beam epitaxy; Annealing; Atomic force microscopy

Carbon nanodot arrays grown as replicas of specially widened anodic aluminum oxide pore arrays by P.J. Zhang; J.T. Chen; R.F. Zhuo; L. Xu; Q.H. Lu; X. Ji; P.X. Yan; Z.G. Wu (pp. 4456-4460).

Via a specially widened anodic aluminum oxide (AAO) pore arrays, carbon nanodot arrays with uniform size and high density were obtained through filtered cathodic arc plasma (FCAP) technique. The AAO template was prepared in oxalic acid by multi-steps to get a specially enlarged opening which plays an important role in the deposition of nanodots. The morphology of the nanodots was studied by a field emission scanning electron microscopy (FESEM). The diameter of the as-prepared nanodot demonstrated here is about 100nm at the bottom and less than 40nm at the top, and the density was estimated to 10¹⁰cm⁻². Field emission properties of the nanodot arrays were investigated and a low threshold field of 5.1V/μm at 10mA/cm² was obtained. In this paper, the carbon nanodot arrays grown as replicas of the specially widened AAO template may support a strategy to realize the fabrication of nanodot arrays with various materials.

Keywords: PACS; 85.45.Db; 81.05.Uw; 61.46.+wNanodot arrays; Anodic aluminum oxide; Filtered cathodic arc plasma; Field emission

Effects of buffer layer annealing temperature on the structural and optical properties of hydrothermal grown ZnO by X.Q. Zhao; C.R. Kim; J.Y. Lee; J.H. Heo; C.M. Shin; H. Ryu; J.H. Chang; H.C. Lee; C.S. Son; W.J. Lee; W.G. Jung; S.T. Tan; J.L. Zhao; X.W. Sun (pp. 4461-4465).

ZnO was deposited on bare Si(100), as-deposited, and annealed ZnO/Si(100) substrates by hydrothermal synthesis. The effects of a ZnO buffer layer and its thermal annealing on the properties of the ZnO deposited by hydrothermal synthesis were studied. The grain size and root mean square (RMS) roughness values of the ZnO buffer layer increased after thermal annealing of the buffer layer. The effect of buffer layer annealing temperature on the structural and optical properties was investigated by photoluminescence, X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Hydrothermal grown ZnO deposited on ZnO/Si(100) annealed at 750°C with the concentration of 0.3M exhibits the best structural and optical properties.

Keywords: PACS; 81.05.Dz; 81.16.Be; 81.40.EfZnO; Hydrothermal synthesis; Buffer layer annealing

Wide band gap Cd_0.83Mg_0.15Al_0.02O thin films by pulsed laser deposition by R.K. Gupta; K. Ghosh; R. Patel; P.K. Kahol (pp. 4466-4469).

Magnesium and aluminum doped CdO thin films were deposited on quartz substrate using pulsed laser deposition technique. Magnesium is used to widen the band gap and aluminum is used to increase carrier concentration of CdO films. The effect of growth temperature on structural, optical, and electrical properties was studied. These films are crystalline in nature and their preferred orientation depends on growth temperature. These films are highly transparent (∼86%) in visible region. The band gap of the films varies from 3.1eV to 3.4eV. The electrical conductivity and carrier concentration were found to decrease with increase in growth temperature.

Keywords: PACS; 72.20; 78.66; 73.50J; 61.16CCadmium oxide; Aluminum oxide; Magnesium oxide; Pulsed laser deposition; Band gap; Hall effect; Mobility

Synthesis and field-emission of aligned SnO₂ nanotubes arrays by Zijiong Li; Haiyan Wang; Ping Liu; Bo Zhao; Yafei Zhang (pp. 4470-4473).

Aligned tin dioxide (SnO₂) nanotubes have been synthesized by high-frequency inductive heating. Nanotubes with high yield were grown on silicon substrates in less than 5min, using SnO₂ and graphite as the source powder. Scanning electron microscopy and transmission electron microscopy showed nanotube with diameters from 50 to 100nm and lengths up to tens of mircrometers. The SnO₂ nanotubes synthesized under the optimum condition have better field-emission characteristics. The turn-on field needed to produce a current density of 10μA/cm² is found to be 1.64V/μm. The samples show good field-emission properties with a fairly stable emission current. This type of SnO₂ nanotubes can be applied as field emitters in displays as well as vacuum electric devices.

Keywords: SnO; ₂; nanotubes; High-frequency inductive heating; Field-emission

Surface modifications of AISI 1045 steel created by high intensity 1064 and 532nm picosecond Nd:YAG laser pulses by J. Stasic; M. Trtica; B. Gakovic; S. Petrovic; D. Batani; T. Desai; P. Panjan (pp. 4474-4478).

Interaction of Nd:YAG laser, operating at 1064 or 532nm wavelength and a pulse duration of 40ps, with AISI 1045 steel was studied. Surface damage thresholds were estimated to be 0.30 and 0.16J/cm² at the wavelengths of 1064 and 532nm, respectively. The steel surface modification was studied at the laser energy density of 10.3J/cm² (at 1064nm) and 5.4J/cm² (at 532nm). The energy absorbed from Nd:YAG laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following AISI 1045 steel surface morphological changes and processes were observed: (i) both laser wavelengths cause damage of the steel in the central zone of irradiated area; (ii) appearance of a hydrodynamic feature in the form of resolidified droplets of the material in the surrounding outer zone with 1064nm laser wavelength; (iii) appearance of periodic surface structures, at micro- and nano-level, with the 532nm wavelength and, (iv) development of plasma in front of the target. Generally, interaction of laser beam with the AISI 1045 steel (at 1064 and 532nm) results in a near-instantaneous creation of damage, meaning that large steel surfaces can be processed in short time.

Keywords: AISI 1045 steel; Laser-matter interaction; Picosecond Nd:YAG laser

A simple method for the preparation of superhydrophobic PVDF–HMFS hybrid composite coatings by Bharathi Bai J. Basu; Ashok Kumar Paranthaman (pp. 4479-4483).

A superhydrophobic surface was obtained by embedding hydrophobically modified fumed silica (HMFS) particles in polyvinylidene fluoride (PVDF) matrix. The water contact angle (WCA) on the PVDF–HMFS hybrid composite coating is influenced by the content and nature of silica particles in the coating. As the silica concentration in PVDF matrix was increased from 33.3% to 71.4%, WCA increased from 117° to 168° and the sliding angle decreased from 90° to <1°. Surface topography of the coating was examined using scanning electron microscopy. An irregular rough surface structure composed of microcavities and nanofilaments was found to be responsible for the superhydrophobicity. The method is simple and cost-effective and can be used for preparing self-cleaning superhydrophobic coating on large areas of different substrates.

Keywords: Superhydrophobic; Polyvinylidene fluoride; PVDF; Coatings; Hydrophobically modified fumed silica; Water contact angle

Effect of temperature on residual stress and mechanical properties of Ti films prepared by both ion implantation and ion beam assisted deposition by Yue He; Jizhong Zhang; Wenqing Yao; Dexing Li; Xu Teng (pp. 4484-4490).

Ti films with a thickness of 1.6μm (group A) and 4.6μm (group B) were prepared on surface of silicon crystal by metal vapor vacuum arc (MEVVA) ion implantation combined with ion beam assisted deposition (IBAD). Different anneal temperatures ranging from 100 to 500°C were used to investigate effect of temperature on residual stress and mechanical properties of the Ti films. X-ray diffraction (XRD) was used to measure residual stress of the Ti films. The morphology, depth profile, roughness, nanohardness, and modulus of the Ti films were measured by scanning electron microscopy (SEM), scanning Auger nanoprobe (SAN), atomic force microscopy (AFM), and nanoindentation, respectively. The experimental results suggest that residual stress was sensitive to film thickness and anneal temperature. The critical temperatures of the sample groups A and B that residual stress changed from compressive to tensile were 404 and 428°C, respectively. The mean surface roughness and grain size of the annealed Ti films increased with increasing anneal temperature. The values of nanohardness and modulus of the Ti films reached their maximum values near the surface, then, reached corresponding values with increasing depth of the indentation. The mechanism of stress relaxation of the Ti films is discussed in terms of re-crystallization and difference of coefficient of thermal expansion between Ti film and Si substrate.

Keywords: PACS; 68.60.Dv; 81.40.Ef; 65.40.De; 83.85.StTitanium; Residual stress; MEVVA; IBAD; Nanohardness; XRD

Electrical conductivity and optical properties of ZnO nanostructured thin film by Mujdat Caglar; Saliha Ilican; Yasemin Caglar; Fahrettin Yakuphanoglu (pp. 4491-4496).

The electrical conductivity, structural and optical properties of ZnO nanostructured semiconductor thin film prepared by sol–gel spin coating method have been investigated. The X-ray diffraction result indicates that the ZnO film has the polycrystalline nature with average grain size of 28nm. The optical transmittance spectrum indicates the average transmittance higher than 90% in visible region. The optical band gap, Urbach energy and optical constants (refractive index, extinction coefficient, real and imaginary parts of the dielectric constant) of the film were determined. The electrical conductivity of the film dependence of temperature was measured to identify the dominant conductivity mechanism. The conductivity mechanism of the film is the thermally activated band conduction. The electrical conductivity and optical results revealed that the ZnO film is an n-type nanostructured semiconductor with a direct band gap of about 3.30eV at room temperature.

Keywords: ZnO; Nanostructured thin film; Sol–gel spin coating; Optical constants

Fabrication of nanocomposites by collagen templated synthesis of layered double hydroxides assisted by an acrylic silane coupling agent by Yanqing Sun; Yuming Zhou; Zhiqiang Wang; Xiaoyun Ye (pp. 4497-4502).

The purpose of this study was to control the fabrication of nanocomposites at the nanoscale interface by collagen templated synthesis of Zn–Al layered double hydroxides (LDHs) assisted by γ-methacryloxypropyl trimethoxy silane (KH570) with further treatment of graft polymerization. The results show that collagen directs the growth of LDHs into curved nanorods by length of 300nm in perfect consistency with collagen chain in both the size and flexility under the essential hydrophobic environment on the solid surface provided by KH570. The nanorods are aggregated into thin curved platelets due to strong interaction between collagen molecules themselves and strong interaction between collagen and LDH sheets. By further treatment of graft polymerization, the adjacent curved platelets encircle into numerous hollows via chemical linkage, achieving polyporous nanocomposites. Nanohybrid materials with this structure are especially interesting for applications as biosensors or supported catalysis.

Keywords: PACS; 81.07.Pr; 82.35.Np; 64.60.Qb; 78.66.Sq; 68.55.AcLayered double hydroxides; Collagen; KH570; Template; Nanocomposites

Processing for optically active erbium in silicon by film co-deposition and ion-beam mixing by S. Abedrabbo; Q. Mohammed; A.T. Fiory (pp. 4503-4511).

Techniques of film deposition by co-evaporation, ion-beam assisted mixing, oxygen ion implantation, and thermal annealing were been combined in a novel way to study processing of erbium-in-silicon thin-film materials for optoelectronics applications. Structures with erbium concentrations above atomic solubility in silicon and below that of silicide compounds were prepared by vacuum co-evaporation from two elemental sources to deposit 200–270nm films on crystalline silicon substrates. Ar⁺ ions were implanted at 300keV. Oxygen was incorporated by O⁺-ion implantation at 130keV. Samples were annealed at 600°C in vacuum. Concentration profiles of the constituent elements were obtained by Rutherford backscattering spectrometry. Results show that diffusion induced by ion-beam mixing and activated by thermal annealing depends on the deposited Si–Er profile and reaction with implanted oxygen. Room temperature photoluminescence spectra show Er³⁺ transitions in a 1480–1550nm band and integrated intensities that increase with the oxygen-to-erbium ratio.

Keywords: PACS; 85.40.Sz; 85.40.Ry; 61.80.Jh; 61.72.sd; 68.55.at; 78.55.HxErbium optoelectronics; Ion-beam processing; Enhanced diffusion

Highly oriented pyrolitic graphite anomalous structures and fullerenes self-assembly by L.S. Pinheiro; J.A.K. Freire (pp. 4512-4514).

Scanning tunneling microscopy (STM) was used to look for unusual self-structures on highly oriented pyrolitic graphite (HOPG) that can mimic fullerenes assemblies. HOPG features that may be taken as C₆₀ molecular structures were found on this surface. The HOPG self-structures have been presented earlier as anomalies of the bare HOPG surface in the literature. The experimental results are in agreement with earlier STM reports on bare and modified HOPG.

Keywords: PACS; 68.43.−h; 68.35.bp; 81.05.uw; 68.37.EfAdsorption; C60; HOPG; Scanning tunneling microscopy

Picosecond pulsed laser ablation and micromachining of 4H-SiC wafers by Pal Molian; Ben Pecholt; Saurabh Gupta (pp. 4515-4520).

Ultra-short pulsed laser ablation and micromachining of n-type, 4H-SiC wafer was performed using a 1552nm wavelength, 2ps pulse, 5μJ pulse energy erbium-doped fiber laser with an objective of rapid etching of diaphragms for pressure sensors. Ablation rate, studied as a function of energy fluence, reached a maximum of 20nm per pulse at 10mJ/cm², which is much higher than that achievable by the femtosecond laser for the equivalent energy fluence. Ablation threshold was determined as 2mJ/cm². Scanning electron microscope images supported the Coulomb explosion (CE) mechanism by revealing very fine particulates, smooth surfaces and absence of thermal effects including melt layer formation. It is hypothesized that defect-activated absorption and multiphoton absorption mechanisms gave rise to a charge density in the surface layers required for CE and enabled material expulsion in the form of nanoparticles. Trenches and holes micromachined by the picosecond laser exhibited clean and smooth edges and non-thermal ablation mode for pulse repetition rates less than 250kHz. However carbonaceous material and recast layer were noted in the machined region when the pulse repetition rate was increased 500kHz that could be attributed to the interaction between air plasma and micro/nanoparticles. A comparison with femtosecond pulsed lasers shows the promise that picosecond lasers are more efficient and cost effective tools for creating sensor diaphragms and via holes in 4H-SiC.

Keywords: Laser; Ultra-short pulse; Ablation; Micromachining; Silicon carbide; MEMS

The influence of Co doping on the dielectric, ferroelectric and ferromagnetic properties of Ba_0.70Sr_0.30TiO₃ thin films by Lina Gao; Jiwei Zhai; Xi Yao (pp. 4521-4525).

Ba_0.70Sr_0.30TiO₃ (BST) thin films doped by Co (BSTC) are fabricated by sol–gel method on a Pt/Ti/SiO₂/Si substrate. A strong correlation is observed among the microstructure, dielectric, ferroelectric, ferromagnetic properties and Co concentration. The dielectric constant of BST thin films can be tailored from 343 to 119 by manipulating the Co concentration. The dielectric loss of BSTC thin films are still kept below 0.020 and the tunability is above 30% at a dc-applied electric field of 500kV/cm. With increasing Co doping up to 10mol%, the coexistence of ferromagnetism and ferroelectrics is found. Suitable dielectric constant, low-dielectric loss, and high tunability of this kind of thin films can be useful for potential tunable applications.

Keywords: PACS; 77.80.−e; 77.22.Ch; 77.55.+f; 77.80.Bh; 76.50.+gSol–gel; Thin films; Dielectric properties; Ferroelectric; Ferromagnetism

Direct writing of carbon nanotube patterns by laser-induced chemical vapor deposition on a transparent substrate by J.B. Park; M.S. Jeong; S.H. Jeong (pp. 4526-4530).

Dot array and line patterns of multi-walled carbon nanotubes (MWCNTs) were successfully grown by laser-induced chemical vapor deposition (LCVD) on a transparent substrate at room temperature. In the proposed technique, a Nd:YVO₄ laser with a wavelength of 532nm irradiates the backside of multiple catalyst layers (Ni/Al/Cr) through a transparent substrate to induce a local temperature rise, thereby allowing the direct writing of dense dot and line patterns of MWCNTs below 10μm in size to be produced with uniform density on the controlled positions. In this LCVD method, a multiple-catalyst-layer with a Cr thermal layer is the central component for enabling the growth of dense MWCNTs with good spatial resolution.

Keywords: PACS; 81.16.Mk; 81.07.De; 81.16.HcLaser chemical vapor deposition; Carbon nanotube; Laser direct writing; Multiple-catalyst-layer

Effects of vanadium doping on structure and electrical properties of SrBi₄Ti₄O₁₅ thin films by Dalhyun Do; Sang Su Kim; Jin Won Kim (pp. 4531-4535).

The effects of vanadium(V) doping into SrBi₄Ti₄O₁₅ (SBTi) thin films on the structure, ferroelectric, leakage current, dielectric, and fatigue properties have been studied. X-ray diffraction result showed that the crystal structure of the SBTi thin films with and without vanadium is the same. Enhanced ferroelectricity was observed in the V-doped SrBi₄Ti₄O₁₅ (SrBi4− x_/3Ti4−_xV_xO₁₅, SBTiV- x ( x=0.03, 0.06, and 0.09)) thin films compared to the pure SrBi₄Ti₄O₁₅ thin film. The values of remnant polarization (2 P_r) and coercive field (2 E_c) of the SBTiV-0.09 thin film capacitor were 40.9μC/cm² and 105.6kV/cm at an applied electric field of 187.5kV/cm, respectively. The 2 P_r value is over five times larger than that of the pure SBTi thin film capacitor. At 100kHz, the values of dielectric constant and dielectric loss were 449 and 0.04, and 214 and 0.06 for the SBTiV-0.09 and the pure SBTi thin film capacitors, respectively. The leakage current density of the SBTiV-0.09 thin film capacitor measured at 100kV/cm was 6.8×10⁻⁹A/cm², which is more than two and a half orders of magnitude lower than that of the pure SBTi thin film capacitor. Furthermore, the SBTiV-0.09 thin film exhibited good fatigue endurance up to 10¹⁰ switching cycles. The improved electrical properties may be related to the reduction of internal defects such as bismuth and oxygen vacancies with changes in the grain size by doping of vanadium into SBTi.

Keywords: SrBi; ₄; Ti; ₄; O; ₁₅; thin film; Chemical solution deposition; Ferroelectric properties; Leakage current; Dielectric properties; Fatigue characteristics

Enhanced field emission from Si doped nanocrystalline AlN thin films by R. Thapa; B. Saha; K.K. Chattopadhyay (pp. 4536-4541).

Si doped and undoped nanocrystalline aluminum nitride thin films were deposited on various substrates by direct current sputtering technique. X-ray diffraction analysis confirmed the formation of phase pure hexagonal aluminum nitride with a single peak corresponding to (100) reflection of AlN with lattice constants, a=0.3114nm and c=0.4986nm. Energy dispersive analysis of X-rays confirmed the presence of Si in the doped AlN films. Atomic force microscopic studies showed that the average particle size of the film prepared at substrate temperature 200°C was 9.5nm, but when 5at.% Si was incorporated the average particle size increased to ∼21nm. Field emission study indicated that, with increasing Si doping concentration, the emission characteristics have been improved. The turn-on field ( E_to) was 15.0 (±0.7)V/μm, 8.0 (±0.4)V/μm and 7.8 (±0.5)V/μm for undoped, 3at.% and 5at.% Si doped AlN films respectively and the maximum current density of 0.27μA/cm² has been observed for 5at.% Si doped nanocrystalline AlN film. It was also found that the dielectric properties were highly dependent on Si doping.

Keywords: PACS; 68.55.−a; 77.55.+f; 79.70.+qAlN thin film; Si doping; Dielectric property; Field emission

Preparation and microwave absorption properties of electroless Co–P-coated nickel hollow spheres by Zhibin Li; Bin Shen; Yida Deng; Lei Liu; Wenbin Hu (pp. 4542-4546).

Co–P-coated nickel hollow spheres (NHSs) were prepared by electroless plating technology. The morphology and component content of Co–P coating varies with the change of sodium citrate concentration in elctroless plating solution. And as phosphorus content increases in coatings, resulting in smaller grain, coercivity of microspheres decreases. The microwave absorption properties of spheres–wax composite were investigated in the range of 2–18GHz. Both permittivity and permeability increase with an increase of cobalt content in coatings. For composite layer, a minimal reflection loss (RL, −36.9dB) of was predicted at 8.1GHz with a thickness of 3mm.

Keywords: Hollow spheres; Electroless plating technology; Microwave absorption properties

Annealing temperature dependence of Raman scattering in Si/SiO₂ superlattice prepared by magnetron sputtering by Shihua Huang; Hong Xiao; Sha Shou (pp. 4547-4550).

Si/SiO₂ superlattices were prepared by magnetron sputtering, and the deposition temperature and annealing temperature had a great influence on the superlattice structure. In terms of SEM images, the mean size of Si nanocrystals annealed at 1100°C is larger than that of nanocrystals annealed at 850°C. It was found that the films deposited at room temperature are amorphous. With increasing deposition temperature, the amorphous and crystalline phases coexist. With increasing annealing temperature, the Raman intensity of the peak near 470cm⁻¹ decreases, and the intensity of that at 520cm⁻¹ increases. Also, on increasing the annealing temperature, the Raman peak near 520cm⁻¹ shifts and narrows, and asymmetry emerges. A spherical cluster is used to model the nanocrystals in Si/SiO₂ superlattices, and the observed Raman spectra are analyzed by combining the effects of confinement on the phonon frequencies. Raman spectra from a variety of nanocrystalline silicon structures were successfully explained in terms of the phonon confinement effect. The fitted results agreed well with the experimental observations from SEM images.

Keywords: PACS; 61.72; 80.15.C; 81.40.ESi/SiO; ₂; superlattice; Magnetron sputtering; Raman spectroscopy

Equilibrium, kinetic and thermodynamic studies on the adsorption of the toxins of Bacillus thuringiensis subsp. kurstaki by clay minerals by Qingling Fu; Yali Deng; Huishu Li; Jie Liu; Hongqing Hu; Shouwen Chen; Tongmin Sa (pp. 4551-4557).

The persistence of Bacillus thuringiensis ( Bt) toxins in soil is further enhanced through association with soil particles. Such persistence may improve the effectiveness of controlling target pests, but impose a hazard to non-target organisms in soil ecosystems. In this study, the equilibrium adsorption of the Bt toxin by four clay minerals (montmorillonite, kaolinite, goethite, and silicon dioxide) was investigated, and the kinetic and thermodynamic parameters were calculated. The results showed that Bt toxin could be adsorbed easily by minerals, and the adsorption was much easier at low temperature than at high temperature at the initial concentration varying from 0 to 1000mgL⁻¹. The adsorption fitted well to both Langmuir and Freundlich isotherm models, but the Freundlich equation was more suitable. The pseudo-second-order (PSO) was the best application model to describe the adsorption kinetic. The adsorption process appeared to be controlled by chemical process, and the intra-particle diffusion was not the only rate-controlling step. The negative standard free energy (ΔGmθr) values of the adsorption indicated that the adsorption of the Bt toxin by the minerals was spontaneous, and the changes of the standard enthalpy (ΔHmθr) showed that the adsorption of the Bt toxin by montmorillonite was endothermic while the adsorption by the other three minerals was exothermic.

Keywords: PACS; 05.20.Dd; 05.70.Np; 45.50.−j; 47.54.Fj; 47.57.J−; 68.43.Mn; 68.47.Gh Bt; toxin; Equilibrium of adsorption; Kinetic of adsorption; Clay minerals; Thermodynamic of adsorption

Nanoindentation and nanoscratch behaviors of Ag/Ni multilayers by S.P. Wen; R.L. Zong; F. Zeng; S. Guo; F. Pan (pp. 4558-4562).

The hardness, elastic modulus and scratch behaviors of Ag/Ni mulitlayers deposited by evaporation have been carried out by nanoindentation and nanoscratch. It has been found that the hardness ( H) increases, while the modulus ( E) decreases, that is to say an increase of H/ E as the periodicity decreases. Many mechanisms are included in nanoscratch, including initial elastic contact, plowing and fracture stage, in each multilayer. Coefficient of friction during plowing decreases with the decrease of the periodicity, which can be ascribed to decreasing material pile-up due to the increase of H/ E. Elastic recovery after scratching also increases as the periodicity decreases because of the increase of H/ E, which leads to improved wear resistance. The fracture stage will be postponed with decreasing periodicity, which also leads to better wear behavior.

Keywords: PACS; 62.20.Qp; 62.25.+gNanoindentation; Nanoscratch; Coefficient of friction; H; /; E

Characteristics of polymer velvet as field emitters under high-current pulsed discharge by Limin Li; Lie Liu; Lei Chang; Hong Wan; Jianchun Wen; Yonggui Liu (pp. 4563-4568).

In this paper we investigated the surface morphology and emission property of polymer velvet in a cathode test system powered by a ∼400ns, ∼400kV pulsed generator. After a series of pulse shots, the velvet surface exhibited an obvious decrease in the amount of emitters, namely, the smoothing of microprotrusions, indicating a lower field enhancement factor or a higher turn-on electric field than that for no shots. As the velvet cathode lifetime proceeded, the beam degradation was observed in terms of the voltage pulse length, maximum emission current, and rise time of diode current. Further, the average current density significantly decreased during a 100 pulse shot test, from 280 to 160A/cm². The surface discharge caused many plasma spots on the velvet surface. The cathode plasma expands towards the anode, directly leading to the diode gap closure. The degradation in the velvet performance after high-current emission may be related to this behavior of cathode plasma. Finally, the electron emission mechanisms, how to affect the surface morphology of velvet, are presented.

Keywords: Polymer velvet; Emission property; Surface morphology; Pulsed discharge

Adsorption/desorption behavior of protein on nanosized hydroxyapatite coatings: A quartz crystal microbalance study by Zhengpeng Yang; Chunjing Zhang (pp. 4569-4574).

Protein separation relates closely to the interactions between proteins and various kinds of adsorbents. To obtain a direct and comprehensive understanding of the protein interaction at the solid/solution interface, quartz crystal microbalance (QCM) technique was employed to in situ investigate the adsorption process of bovine serum albumin (BSA) on nanosized hydroxyapatite coatings, and factors affecting its adsorption such as pH, solution ionic strength and temperature were discussed in detail. The adsorption kinetic parameter and the desorption of adsorbed BSA caused by phosphate buffer solution (PBS) introduction were investigated and discussed as well, and an adsorption/desorption mechanism has been proposed. The obtained information suggests that QCM is a useful method for monitoring the adsorption/desorption behavior of BSA on nanosized hydroxyapatite coating.

Keywords: Bovine serum albumin; Nanosized hydroxyapatite coatings; Adsorption; Desorption; Quartz crystal microbalance

Easy fabrication of large-size superhydrophobic surfaces by atmospheric pressure plasma polymerization with non-polar aromatic hydrocarbon in an in-line process by Young-Yeon Ji; Sang-Sik Kim; O.-Pil Kwon; Suck-Hyun Lee (pp. 4575-4578).

We report on the formation of superhydrophobic surfaces on glass by plasma polymerization with non-polar aromatic hydrocarbon, at atmospheric pressure, in an in-line process. The glass was simply treated by radio frequency (RF) plasma with a mixture of toluene and hexamethyldisiloxane (HMDSO). The hydrophobicity of the sample surfaces increase with increasing plasma treatments; contact angles of 150° for water droplets are achieved. It is attributed mainly to its high content of non-polar hydrophobic phenyl groups and its rough surface.

Keywords: Plasma polymerization; Toluene/hexamethyldisiloxane; Superhydrophobicity

Effect of thickness on structural, optical and electrical properties of nanostructured ZnO thin films by spray pyrolysis by T. Prasada Rao; M.C. Santhoshkumar (pp. 4579-4584).

Transparent conducting zinc oxide thin films were prepared by spray pyrolytic decomposition of zinc acetate onto glass substrates with different thickness. The crystallographic structure of the films was studied by X-ray diffraction (XRD). XRD measurement showed that the films were crystallized in the wurtzite phase type. The grain size, lattice constants and strain in films were calculated. The grain size increases with thickness. The studies on the optical properties show that the direct band gap value increases from 3.15 to 3.24eV when the thickness varies from 600 to 2350nm. The temperature dependence of the electrical conductivity during the heat treatment was studied. It was observed that heat treatment improve the electrical conductivity of the ZnO thin films. The conductivity was found to increase with film thickness.

Keywords: PACS; 61.10.Nz; 71.55.Gs; 73.61.Ga; 78.66.Hf; 81.15.RsZinc oxide; Spray pyrolysis; Strain; Chemisorption

Electrical behavior of BaZr_0.1Ti_0.9O₃ and BaZr_0.2Ti_0.8O₃ thin films by Hongwei Chen; Chuanren Yang; Jihua Zhang; Bo Wang; Hong Ji (pp. 4585-4589).

BaZr_0.1Ti_0.9O₃ and BaZr_0.2Ti_0.8O₃ (BZT) thin films were deposited on Pt/Ti/LaAlO₃ (100) substrates by radio-frequency magnetron sputtering, respectively. The films were further annealed at 800°C for 30min in oxygen. X-ray diffraction θ–2θ and Φ-scans showed that BaZr_0.1Ti_0.9O₃ films displayed a highly ( h00) preferred orientation and a good cube-on-cube epitaxial growth on the LaAlO₃ (100) substrate, while there are no obvious preferential orientation in BaZr_0.2Ti_0.8O₃ thin films. The BaZr_0.1Ti_0.9O₃ films possess larger grain size, higher dielectric constant, larger tunability, larger remanent polarization and coercive electric field than that of BaZr_0.2Ti_0.8O₃ films. Whereas, BaZr_0.1Ti_0.9O₃ films have larger dielectric losses and leakage current density. The results suggest that Zr⁴⁺ ion can decrease dielectric constant and restrain non-linearity. Moreover, the enhancement in dielectric properties of BaZr_0.1Ti_0.9O₃ films may be attributed to (100) preferred orientation.

Keywords: PACS; 77.55.+f; 68.55.−a; 74.62.BfBarium zirconium titanate; Thin film; Zr/Ti ratio; Preferred orientation; Ferroelectric properties

The effect of Ag addition on the optical properties of Se₉₀Te₁₀ films by A.E. Bekheet; N.A. Hegab; M.A. Afifi; H.E. Atyia; E.R. Sharaf (pp. 4590-4594).

Se₉₀Te10−_xAg_x (0≤ x≤6) compositions were prepared by quenching technique. Thin films with different thicknesses of the obtained compositions were deposited on dry clean glass substrates by thermal evaporation technique. Energy dispersive X-ray spectroscopy (EDX) indicates that samples are nearly stoichiometric. X-ray diffraction patterns indicate that they are in the amorphous state. The optical constants, the refractive index n and the absorption index k, have been calculated from transmittance T and reflectance R through the spectral range of 400–2500nm for the studied films with different thicknesses (165–711nm). From the analysis of refractive index n data, high frequency dielectric constant ɛ_∞ was determined. Both ɛ_∞ and n are found to decrease with the increase of Ag content. The optical band gapEgopt is calculated for all compositions from the absorption coefficient analysis. The effect of the Ag addition on the obtained optical parameters has been discussed. The analysis of absorption index k data, revealed the existence of allowed indirect transitions for all compositions. It is indicated also thatEgopt increase with increasing Ag content.

Keywords: Optical constants; Energy gap

Effect of ionization on laser-induced plume self-similar expansion by D. Bennaceur-Doumaz; M. Djebli (pp. 4595-4599).

The dynamics of a laser ablation plume during the first stage of its expansion, just after the termination of the laser pulse is modelled. The one-dimensional expansion of the evaporated material, considered as an ideal fluid, is governed by one-fluid Euler equations. For high energetic ions, the charge separation can be neglected and the hydrodynamics equations solved using self-similar formulation. Numerical solution is obtained, first when the laser fluence range is low enough to deal with a neutral vapor, and in a second stage, when ionization effects on the expansion are taken into account, for different material targets. As a main result, we found that the presence of ions in the evaporated gas enhances the self-similar expansion.

Keywords: PACS; 52.30.q; 52.38.MfPlume expansion; Laser ablation; Self-similar

A study of electrodeposition of CuInSe₂ thin films with triethanolamine as the complexing agent by Thou-Jen Whang; Mu-Tao Hsieh; Ya-Chun Kao; Shyan-Jer Lee (pp. 4600-4605).

In this article, the electrochemistry of CuInSe₂ and its compositional ingredients CuCl₂, InCl₃ and SeO₂ in aqueous solution were investigated. Triethanolamine was added in the single-step electrodeposition of CuInSe₂ from aqueous solution as the complexing agent in order to improve the crystallinity and uniformity of the layer. The stoichiometry, crystal structure and grain sizes of CuInSe₂ thin films of various deposition conditions were compared. The deposition parameters such as the concentration of complexing agent, deposition potential, deposition time and annealing temperature are found to be important factors in the processes of electrical deposition of CuInSe₂ thin films.

Keywords: PACS; 82.45.Vp; 73.50.PzTriethanolamine; Electrodeposition; CuInSe; ₂; Solar cells; ITO

Influences of laser remelting on microstructure of nanostructured Al₂O₃–13wt.% TiO₂ coatings fabricated by plasma spraying by Dongsheng Wang; Zongjun Tian; Lida Shen; Zhidong Liu; Yinhui Huang (pp. 4606-4610).

The effects of laser remelting on microstructure of nanostructured Al₂O₃–13wt.% TiO₂ ceramic coatings prepared by plasma spraying with agglomerated powders were studied. The microstructure of the feedstock, as-sprayed and laser-remelted coatings were investigated by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). The results indicate that the plasma-sprayed ceramic coating consists of both fully melted regions and partially melted regions. The totally ceramic coating, especially the fully melted regions, has a typical plasma-sprayed lamellar-like structure as the conventional coating, and has some pores. According to the difference of microstructures, the partially melted regions can be divided into liquid-phase sintered regions (a three-dimensional net or skeleton-like structure: Al₂O₃-rich submicron particles embedded in the TiO₂-rich matrix) and solid-phase sintered regions (remained nanoparticles). The lamellar defect of the as-sprayed coating is erased, and the compactness of the coating is improved significantly after laser remelting. The laser-remelted region composed of fine equiaxed grains, which are different from the conventional column-like crystals along the direction of the heat current. Due to the rapid solidification of laser remelting process, there are still some nanoparticles in the remelted region because of an insufficient time for grains growth.

Keywords: Laser remelting; Plasma spraying; Nanostructured coatings; Al; ₂; O; ₃; –13; wt.% TiO; ₂; Microstructure

Growth of Y-junction bamboo-shaped CN_x nanotubes on GaAs substrate using single feedstock by Pradip Ghosh; M. Subramanian; R.A. Afre; M. Zamri; T. Soga; T. Jimbo; V. Filip; M. Tanemura (pp. 4611-4615).

Nitrogen-doped Y-junction bamboo-shaped carbon nanotubes were synthesized by chemical vapor deposition of monoethanolamine/ferrocene mixture on GaAs substrate at 950°C. The use of monoethanolamine as the C/N feedstock simplifies the experimental arrangement by producing ammonia during the growth process. The structure, morphology and graphitization of as-grown nitrogen-doped carbon nanotubes (CN_x) were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy analysis. TEM analysis indicates that nanotubes have a bamboo-like structure. The nitrogen concentration on as-grown CN_x nanotube was found to be 7.8at.% by X-ray photoelectron spectroscopy (XPS) analysis. XPS analysis also indicated that there are two different types of nitrogen atoms (pyridinic and graphitic) in these materials. The possible growth mechanism of formation of Y-junction CN_x nanotubes was briefly discussed. Field emission measurement suggested that as-grown CN_x nanotubes are excellent emitters with turn-on and threshold fields of 1.6 and 2.63V/μm, respectively. The result indicated that monoethanolamine proves to be an advantageous precursor to synthesize Y-junction nitrogen-doped carbon nanotubes and such nanotubes might be an effective material to fabricate various field emission devices.

Keywords: PACS; 61.48.De; 81.15.Gh; 81.07.De; 79.70.+qN-Doped carbon nanotubes; Y-Junction; Chemical vapor deposition; Field electron emission

Effects of H₂ ambient annealing in fully 002-textured ZnO:Ga thin films grown on glass substrates using RF magnetron co-sputter deposition by Sungyeon Kim; Jungmok Seo; Hyeon Woo Jang; Jungsik Bang; Woong Lee; Taeyoon Lee; Jae-Min Myoung (pp. 4616-4622).

Gallium doped zinc oxide (ZnO:Ga) thin films were grown on glass substrates using RF magnetron co-sputtering, followed by H₂ ambient annealing at 623K to explore a possibility of steady and low-cost process for fabricating transparent electrodes. While it was observed that the ZnO:Ga thin films were densely packed c-axis oriented self-textured structures, in the as-deposited state, the films contained Ga₂O₃ and ZnGa₂O₄ which had adverse effect on the electrical properties. On the other hand, post-annealing in H₂ ambient improved the electrical properties significantly via reduction of Ga₂O₃ and ZnGa₂O₄ to release elemental Ga which subsequently acted as substitutional dopant increasing the carrier concentration by two orders of magnitude. Transmittance of the ZnO:Ga thin films were all over 90% that of glass while the optical band gap varied in accordance with the carrier concentrations due to changes in Fermi level. Experimental observation in this study suggests that transparent conductive oxide (TCO) films based on Ga doped ZnO with good electrical and optical properties can be realized via simple low-cost process.

Keywords: PACS; 42.79.−e; 61.72.−y; 68.37.Hk; 68.37.Ps; 68.55.−a; 68.55.Ln; 73.61.−r; 78.20.−e; 81.15.Cd; 82.80.−dDoping (A1); X-ray diffraction (A1); Physical vapor deposition processes (A3); Gallium compounds (B1); Zinc compounds (B1); Semiconducting materials (B2)

Synthesis of Fe₃O₄@LaF₃:Ce,Tb nanocomposites with bright fluorescence and strong magnetism by H. He; M.Y. Xie; Y. Ding; X.F. Yu (pp. 4623-4626).

In this paper, fluorescent-magnetic Fe₃O₄@LaF₃:Ce,Tb nanocomposites were synthesized by combining fluorescent LaF₃:Ce,Tb and magnetic Fe₃O₄ nanoparticles into new ‘two-in-one’ entities. The obtained Fe₃O₄@LaF₃:Ce,Tb nanocomposites were small (about 30nm in diameter) and well dispersed in water. Under ultraviolet light irradiation, the Fe₃O₄@LaF₃:Ce,Tb nanocomposites emitted bright green fluorescence, and they could be easily manipulated by an external magnetic field. Such bifunctional nanocomposites may find many biomedical applications, such as cancer detection and drug delivery. And the method we used can be extended to the synthesis of other nanocomposites based on lanthanide-doped materials and metal oxides.

Keywords: PACS; 42.65.Lm; 76.30.Kg; 78.67.BfBifunctional nanocomposites; Fluorescent; Magnetic; Lanthanide-doped

Application of the Statistical Rate Theory of interfacial transport to investigate the kinetics of mixed-gas adsorption onto the energetically homogeneous and strongly heterogeneous surfaces by Krzysztof Nieszporek (pp. 4627-4635).

Kinetics of mixed-gas adsorption by using the Statistical Rate Theory is studied. Applying the adsorption lattice model two cases are investigated: when adsorption occurs like on the homogeneous surface and when energetic heterogeneity of adsorption system can be described by the rectangular adsorption energy distribution function. The model of calculations offers possibility of theoretical prediction of the rate of adsorption/desorption of mixture components by using the single-gas equilibrium and kinetic data. Possible changes of adsorbate concentration near the adsorbing surface are also taken into account. The obtained theoretical expressions were verified using real adsorption systems.

Keywords: Adsorption; Kinetics; Statistical thermodynamics

Field emission from carbon nanotube and tetrapod-like ZnO compound cathode fabricated by spin-coating method by Yunsong Di; Yunkang Cui; Qilong Wang; Wei Lei; Xiaobing Zhang; Daniel den Engelsen (pp. 4636-4639).

We present a study of the field emission properties of a mixture of multi-wall carbon nanotubes (MWCNTs) and tetrapod-like zinc oxide nanostructures (ZTPNs). A spin-coating process instead of screen-printing was used to fabricate the cathode; this prevented largely the destruction of the slim needles of ZTPNs by mechanical rubbing. The protruding needles of ZTPNs in the paste are largely responsible for the field emission, while the CNTs have been added to improve the conductivity of cathode. Ultra low turn-on field at 0.6V/μm and threshold field at 1.5V/μm were obtained; moreover, the emission uniformity improved substantially compared to unmixed samples of ZTPN.

Keywords: Zinc oxide tetrapod-like nanostructure; Carbon nanotube; Compound cathode; Spin-coating

Effect of crystallization on the property of hard enamel coating on steel substrate by Deqing Wang (pp. 4640-4645).

Crystallization treatment was conducted to improve hardness of an enamel coating on steel. Microstructure change of the enamel steel interface was observed. Phase transformation of the glassy enamel was analyzed, and adhesion of the enamel to steel was evaluated. As crystallization time increases, the as-fired enamel/steel interface roughens, protrudes to form anchor points and develops into dendrites growing into grain boundaries of the steel substrate. An adherence factor η is proposed to predict the adherence of the enamel/substrate interface metallographically. Microhardness of the enamel increases from 582HV_0.05 as-fired to 991HV_0.05 after crystallization treatment at 840°C for 20min, which is attributed to the transformation of the vitreous enamel into NaAlSi₂O₆ crystals during the crystallization treatment. Microstructure observation indicates that the white needle-like NaAlSi₂O₆ crystals in the as-fired glassy enamel matrix is increased in number and their morphology change from large aspect ratio into coarsened ones with increasing time at 840°C crystallization treatment. The as-fired enamel coating exhibits an impact energy of 0.81J, and the crystallization treatment at 840°C increases impact energy of the enamel coating from 1.05 to 1.56J with changing crystallization time from 5 to 20min. A regression formula of impact energy associated with adherence factor is obtained to evaluate adhesion of the enamel to steel substrate on the basis of metallographic measurement. The aluminum melt corrosion resistance of the enamel is increased with increasing crystallization of its glassy matrix.

Keywords: PACS; 81.05.Pj; 81.65.−bCrystallization treatment; Microhardness; Enamel coating; Adherence factor; Impact energy

Influence of substoichiometer on the laser-induced damage characters of HfO₂ thin films by Dongping Zhang; Congjuan Wang; Ping Fan; Xingmin Cai; Guangxing Liang; Jianda Shao; Zhengxiu Fan (pp. 4646-4649).

HfO₂ is one of the most important high refractive index materials for depositing high power optical mirrors. In this research, HfO₂ thin films were prepared by dual-ion beam reactive sputtering method, and the laser-induced damage thresholds (LIDT) of the sample were measured in 1-on-1 mode for laser with 1064nm wavelength. The results indicate that the LIDT of the as-grown sample is only 3.96J/cm², but it is increased to 8.98J/cm² after annealing under temperature of 200°C in atmosphere. By measuring the laser weak absorption and SIMS of the samples, we deduced that substoichiometer is the main reason for the low LIDT of the as-grown sample, and the experiment results were well explained with the theory of electronic-avalanche ionization.

Keywords: PACS; 81.15.Cd; 42.70.Hj; 42.79.Wc; 81.40.TvThin film; Dual-ion-beam sputtering; Substoichiometer

Biomass waste-derived activated carbon for the removal of arsenic and manganese ions from aqueous solutions by T. Budinova; D. Savova; B.Tsyntsarski; C.O. Ania; B. Cabal; J.B. Parra; N. Petrov (pp. 4650-4657).

The goal of this study is to investigate the preparation of low-cost activated carbon from bean pods waste and to explore their potential application for the removal of heavy metals from aqueous solutions. Conventional physical (water vapor) activation was used for synthesizing the adsorbent. The obtained carbon was employed for the removal of As (III) and Mn (II) from aqueous solutions at different initial concentrations and pH values. Adsorption for both ions follows Langmuir-type isotherm, the maximum loading capacities for arsenic (III) and Mn (II) ions being 1.01 and 23.4mgg⁻¹, respectively. According to the experimental data, it can be inferred that the basic character of the surface, i.e. the high content of basic groups, favors adsorption of ions. Arsenic adsorption capacity on the carbon obtained from agricultural waste was found to be similar to this of more expensive commercial carbons showing high adsorption capability. Regarding manganese adsorption, herein obtained carbon presented higher uptake adsorption than that of activated carbons reported in the literature.

Keywords: PACS; 61.43.Gt; 68.08.−p; 68.43.−hActivated carbon; Bean pods; Adsorption; Arsenic; Manganese

Structural, optical, and electrical properties of p-type NiO films and composite TiO₂/NiO electrodes for solid-state dye-sensitized solar cells by Yi-Mu Lee; Cheng-Hsing Hsu; Hung-Wei Chen (pp. 4658-4663).

p-Type nickel oxide thin films were prepared by sol–gel method, and their structural, optical and electrical properties were investigated. The Ni(OH)₂ sol was formed from nickel (II) acetate tetrahydrate, Ni(CH₃COO)₂·4H₂O, in a mixture of alcohol solution and poly(ethylene glycol), and deposited on an ITO substrate by spin coating followed by different heat treatments in air (50–800°C). The formation and composition of NiO thin film was justified by EDX analysis. It is found that the thickness of the NiO film calcined at 450°C for 1h is about 120nm with average particle size of 22nm, and high UV transparency (∼75%) in the visible region is also observed. However, the transmittance is negligible for thin films calcined at 800°C and below 200°C due to larger particle size and the amorphous characteristics, respectively. Moreover, the composite electrode comprising n-type TiO₂ and p-type NiO is fabricated. The current–voltage ( I– V) characteristics of the composite TiO₂/NiO electrode demonstrate significant p-type behavior by the shape of the rectifying curve in dark. The effect of calcination temperature on the rectification behavior is also discussed.

Keywords: NiO; Sol–gel coating; p-n junction; Composite electrode; Rectifying characteristics

Dose and pressure dependence of silicon microstructure in SF₆ gas due to excimer laser irradiation by H.R. Dehghanpour; P. Parvin; B. Sajad; S.S. Nour-Azar (pp. 4664-4669).

ArF excimer laser radiation on Si surface at controlled SF₆ atmosphere creates a microstructure whose alteration at various UV doses and SF₆ pressures are investigated in this work. Moreover, a rigorous model has been presented here regarding the experiments based on the micro-fluid mechanical properties of molten silicon layer and the subsequent mechanical wave resonance due to the surface shallow fluid theory. The competitive thermal and non-thermal UV laser interaction with Si and the following heat transfer explains the creation of the self-assembled micro-pillars on Si surface.

Keywords: Si microstructure; ArF laser; Surface wave; Resonance pattern

Metal nanorod production in silicon matrix by electroless process by Shinji Yae; Tatsuya Hirano; Takashi Matsuda; Naoki Fukumuro; Hitoshi Matsuda (pp. 4670-4672).

Metal filled Si nanopores, that is, metal nanorods in an Si matrix, are produced by an electroless process that consists of three steps: (1) electroless displacement deposition of metal nanoparticles from a metal salt solution containing HF; (2) Si nanopore formation by metal-particle-enhanced HF etching; and (3) metal filling in nanopores by autocatalytic electroless deposition. Ag nanoparticles produce Si nanopores whose sizes are a few tens of nm in diameter and ca. 50nm deep. Au nanoparticles produce finer and straighter nanopores on Si than the Ag case. These nanopores are filled with a Co or a Co–Ni alloy by autocatalytic deposition using dimethylamine-borane as a reducing agent. Phosphinate can be used as a reducing agent for the Au-deposited-and-pore-formed Si. The important feature of this process is that the metal nanoparticles, that is, the initiation points of the autocatalytic metal deposition, are present on the bottoms of the Si nanopores.

Keywords: PACS; 62.23.Pq, 81.05.Rm, 81.15.Pq, 81.65.Cf, 82.45.Jn, 82.45.VpMetal nanoparticle; Porous silicon; Metal-particle-enhanced HF etching; Electroless deposition; Magnetic recoding; Cobalt

Effect of sputtering power on surface topography of dc magnetron sputtered Ti thin films observed by AFM by Yongzhong Jin; Wei Wu; Li Li; Jian Chen; Jingyu Zhang; Youbing Zuo; Jun Fu (pp. 4673-4679).

Titanium films were deposited on glass substrates at room temperature by direct current (dc) magnetron sputtering at fixed Ar pressure of 1.7Pa and sputtering time of 4min with different sputtering power ranging from 100 to 300W. Atomic force microscopy (AFM) was used to study topographic characteristics of the films, including crystalline feature, grain size, clustering and roughening. The amorphous-like microstructure feature has been observed at 100–150W and the transition of crystal microstructure from amorphous-like to crystalline state occurs at 200W. The increase in grain size of Ti films with the sputtering power (from 200 to 300W) has been confirmed by AFM characterization. In addition, higher sputtering power (300W) leads to the transformation of crystal texture from globular-like to hexagonal type. The study has shown that higher sputtering power results in the non-linear increase in deposition rate of Ti films. Good correlativity between the surface roughness parameters including root mean square (RMS) roughness, surface mean height (Ra) and maximum peak to valley height ( P– V) for evaluating the lateral feature of the films has been manifested. Surface roughness has an increasing trend at 100–250W, and then drops up to 300W.

Keywords: PACS; 64.70.Nd; 68.37.Ps; 81.07.BcTi films; Magnetron sputtering; Sputtering power; Surface topography; Atomic force microscopy

Optical properties of GdTaO₄:Eu³⁺ thick films prepared from a PVP-containing solution by Xiaolin Liu; Kun Han; Mu Gu; Shiming Huang; Bo Liu; Chen Ni (pp. 4680-4683).

Transparent GdTaO₄:Eu³⁺ thick films were prepared from the inorganic salt and 2-methoxyethanol solution containing polyvinylpyrrolidone (PVP) via sol–gel technique. The critical thickness of the film, i.e. the maximum thickness achievable without crack formation via non-repetitive deposition, was 0.8μm. The effect of PVP on the morphology, crystallization behavior and optical property of the GdTaO₄:Eu³⁺ thick film was investigated. The results indicated that PVP could play an important role in the formation of transparent GdTaO₄:Eu³⁺ thick films, suppressing the stress evolution, adjusting the sol viscosity, ameliorating the crystallinity, and strengthening the covalency of Eu–O bonds. The GdTaO₄:Eu³⁺ thick films prepared with PVP exhibited a superior photoluminescence and X-ray exited luminescence, which implies that it will have promising applications in high-spatial-resolution X-ray imaging and flat panel display devices.

Keywords: PACS; 77.84.Dy; 78.20.−e; 81.20.FwGdTaO; ₄; :Eu; ³⁺; thick film; Polyvinylpyrrolidone; Sol–gel technique; Luminescence

A study on the degradation property of a hydrophilic polycarbonate film treated by inductively coupled plasma using CO₂ as reactive gas by M.C. Kim; T. Masuoka (pp. 4684-4688).

In this study, we report investigations on surface modification of polycarbonate (PC) films for hydrophilicity and degradability under acid/base environmental conditions. The aims of our study were to modify a PC surface by the inductively coupled plasma (ICP) using CO₂ as precursor gas and to confirm the improved hydrophilic and degradable properties. X-ray photoelectron spectroscopy and contact angle measurement were carried out to characterize the chemical binding state and to observe the specific chemical change on the surface, respectively. After the plasma treatment and degradability test, scanning electron microscopy (SEM) was also employed to observe the surface morphologies. The results showed that the CO₂–plasma treatment can be a possible method to improve the hydrophilicity and degradability of the PC surface.

Keywords: ICP; Hydrophilicity; Degradation; Polycarbonate; Carbon dioxide

NiP:Mn as a potential magnetic contacting material to Cd1−_xMn_xTe by Pushan Banerjee; Biswajit Ghosh (pp. 4689-4692).

Injection of spin-polarized current into spintronic devices is a challenge to the semiconductor physicists and technologists. II–VI compound semiconductors can act as the spin aligner on the top of GaAs light emitting diode. However, II–VI compound semiconductor like Cd1−_xMn_xTe is still suffering from contacting problem. Application of electroless deposited magnetic NiP:Mn contact would enhance efficient current injection into Cd1−_xMn_xTe than the standard gold contact. A technique for electroless deposition of NiP:Mn on Cd1−_xMn_xTe have been described here. The electronic and magnetic properties of the contact material NiP:Mn and the contact performance of NiP:Mn relative to evaporated gold have been evaluated. The contact fulfills the requirements of resistivity and ferromagnetism for application to Cd1−_xMn_xTe.

Keywords: PACS; 85.75.–d; 81.05.Dz; 73.40.CgCd; 1−; _x; Mn; _x; Te; Ohmic contact; Electroless deposition; NiP:Mn

Diagnostic study of the roughness surface effect of zirconium on the third-order nonlinear-optical properties of thin films based on zinc oxide nanomaterials by K. Bahedi; M. Addou; M. El Jouad; Z. Sofiani; M. Alaoui Lamrani; T. El Habbani; N. Fellahi; S. Bayoud; L. Dghoughi; B. Sahraoui; Z. Essaïdi (pp. 4693-4695).

Zinc oxide (ZnO) and zirconium doped zinc oxide (ZnO:Zr) thin films were deposited by reactive chemical pulverization spray pyrolysis technique on heated glass substrates at 500°C using zinc and zirconium chlorides as precursors. Effects of zirconium doping agent and surface roughness on the nonlinear optical properties were investigated in detail using atomic force microscopy (AFM) and third harmonic generation (THG) technique. The best value of nonlinear optical susceptibility χ⁽³⁾ was obtained from the doped films with less roughness. A strong third order nonlinear optical susceptibility χ⁽³⁾=20.12×10⁻¹² (esu) of the studied films was found for the 3% doped sample.

Keywords: Spray pyrolysis; ZnO; Zirconium; THG; AFM; Nonlinear Optics

Strong nonlinear optical refractive effect of self-assembled multilayer films containing tetrasulfonated iron phthalocyanine by Chunying He; Wubiao Duan; Guang Shi; Yiqun Wu; Qiuyun Ouyang; Yinglin Song (pp. 4696-4701).

Multilayer films containing anionic iron phthalocyanine tetrasulfonate (FePcTsNa₄) and cationic poly(diallydimethyl ammonium chloride) were prepared using electrostatic self-assembled layer-by-layer technique. The growth of the film was monitored by ultraviolet–visible absorption spectroscopy, and the morphology of the film was characterized by atomic force microscopy. Polarized visible spectra showed that macrocycles of FePcTsNa₄ in the film presented a flat orientation relative to the plane of the solid substrates. The third-order nonlinear optical properties of the film were studied by using Z-scan technique with laser duration of 21ps at the wavelength of 532nm. The FePcTsNa₄/PDDA film exhibited strong self-focusing effect with n₂ value of 4.13×10⁻¹⁵m²/W, which is 4 orders larger than that of FePcTsNa₄ aqueous solution.

Keywords: PACS; 42.65−k; 42.70−aOptical materials and properties; Deposition; Phthalocyanine; Thin film; Z-scan

One-stage fabrication of sub-micron hydrophilic microchannels on PDMS by Zhongkui Wu; Haiying Yan; Hong Chen; He Huang (pp. 4702-4704).

A sub-micron hydrophilic microchannel was fabricated on poly(dimethylsiloxane) (PDMS) in one step using vacuum ultraviolet light (VUV) lithography in vacuum. The topographies and properties of the irradiated PDMS surface were characterized and analyzed by atomic force microscopy (AFM), and the chemical composition changes on VUV-treated PDMS analyzed by X-ray photoelectron spectroscopy (XPS). The hydrophilic stability of irradiated PDMS surface was studied by static water contact angle. As demonstrated, the hydrophilicity on surface of PDMS microchannel can be kept for a longer term even three months after the treatment.

Keywords: Fabrication; Hydrophilic; Microchannel; PDMS; Thin films; VUV; Atomic force microscopy

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Applied Surface Science (v.255, #8)