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Applied Surface Science (v.252, #12)

Investigation on the barrier height and inhomogeneity of nickel silicide Schottky by Shihua Huang; Fang Lu (pp. 4027-4032).

The apparent Schottky barrier height (SBH) of the nickel silicide Schottky contacts annealed at different temperatures was investigated based on temperature dependence of I– V characteristic. Thermionic emission–diffusion (TED) theory, single Gaussian and double Gaussian models were employed to fit I– V experimental data. It is found the single Gaussian and double Gaussian SB distribution model can give a very good fit to the I– V characteristic of apparent SBH for different annealing temperatures. Also, the apparent SBH and the leakage current increase with annealing temperatures under reverse voltage. In addition, the homogeneity of interfaces for the samples annealed at temperatures of 500 and 600°C is much better than that of the samples annealed at temperatures of 400, 700, and 800°C. This may result from the phase transformation of nickel silicide due to the different annealing temperatures and from the low Schottky barrier (SB) patches.

Keywords: PACS; 73.30.+y; 73.40.Ns; 85.30.DeNickel silicide; Schottky barrier inhomogeneities; I; –; V; characteristic; Annealing

In situ monitoring and benchmarking in UHV of InP/GaAsSb heterointerface reconstructions prepared via MOVPE by Z. Kollonitsch; H.-J. Schimper; U. Seidel; F. Willig; T. Hannappel (pp. 4033-4038).

Thin InP layers were grown by metalorganic vapor phase epitaxy on the ternary compound GaAs_0.5Sb_0.5 lattice matched to InP(1 0 0). The heterojunctions were studied with in situ reflectance anisotropy spectroscopy and benchmarked in ultrahigh vacuum with ultraviolet and X-ray photoelectron spectroscopy and low energy electron diffraction with regard to the sharpness of the interface. During growth of GaAs_0.5Sb_0.5 an Sb-rich(1×3)-like reconstruction was observed and during stabilization with TBAs an As-richc(4×4) reconstruction. These two different reconstructions of GaAs_0.5Sb_0.5(1 0 0), well-known from the binaries GaSb(1 0 0) and GaAs(1 0 0) respectively, were used for preparing InP/GaAs_0.5Sb_0.5 heterojunctions. The RA spectra of thin heteroepitaxial InP layers were compared to a well-established RA spectrum of MOVPE-prepared homoepitaxial,(2×1)-like reconstructed P-rich InP(1 0 0), that was used as a reference spectrum of a well defined surface. Growing InP on thec(4×4) reconstructed GaAsSb(1 0 0) surface resulted in a significantly sharper interface than InP growth on(1×3) reconstructed GaAsSb(1 0 0).

Keywords: Reflectance anisotropy spectroscopy; Low energy electron diffraction; Surface reconstruction; Metalorganic vapor phase epitaxy; Antimonides; Semiconducting ternary compounds

The effect of some Schiff bases on the corrosion of aluminum in hydrochloric acid solution by H. Ashassi-Sorkhabi; B. Shabani; B. Aligholipour; D. Seifzadeh (pp. 4039-4047).

The inhibition effect of Schiff bases benzylidene-(2-methoxy-phenyl)-amine (A), (2-methoxy-phenyl)-(4-methyl-benzylidene)-amine (B), (4-chloro-benzylidene)-(2-methoxy-phenyl)-amine (C) and (4-nitro-bezylidene)-(2-methoxy-phenyl)-amine (D) on the corrosion of aluminum in 1M HCl has been studied by polarization, electrochemical impedance spectroscopy (EIS) and weight loss measurements. It has been found that all the studied Schiff bases are excellent inhibitors. Maximum inhibition was obtained for 0.01M Schiff base A. Results show that the inhibition efficiency increases with decreasing in temperature and increasing in concentration of Schiff base. Polarization curves reveal that the used inhibitors are mixed type inhibitors. The surface adsorption of the Schiff bases leads to a decrease of double layer capacitance as well as an increase of polarization resistance. The inhibitor performance depends strongly on the type of function groups substituted on benzene ring. The adsorption of used compounds on the aluminum surface obeys a Langmuir isotherm and has a physical mechanism. Thermodynamic parameters for both dissolution and adsorption processes were determined. The quantum chemical study of the corrosion inhibition efficiency of the Schiff bases on Al in molar HCl was carried out.

Keywords: Aluminum; Corrosion inhibition; Schiff base; HCl

Luminescence properties of spark-processed Si in air, O₂, and N₂ with low pressure by Sung-Sik Chang; Shu Kurokawa; Akira Sakai (pp. 4048-4054).

This paper reports the luminescence properties of spark-processed Si (sp-Si) prepared with different atmospheres such as air, O₂, and N₂ in low vacuum range (50–760Torr). Three main luminescence bands are observed from spark-processed Si (sp-Si). In addition to the well-known two luminescence bands in the blue/violet peaking at 410nm and green peaking at 500nm, a novel UV luminescence band is detected for the sp-Si prepared in N₂. The temperature dependence of photoluminescence (PL) characteristics of the newly detected UV luminescence band is examined. Further studies of photoluminescence excitation (PLE) have been performed and origins of luminescence are discussed based on the experimental results.

Keywords: Optical properties; Photoluminescence; Absorption

Effect of energy distribution of interface states on the electrical characteristics of semiconductor heterojunction diode by P. Chattopadhyay; D.P. Haldar (pp. 4055-4063).

An energy distribution of interface states has been considered to study the electrical characteristics of an anisotype semiconductor heterojunction. Various electrical quantities such as the surface potential, current, conductance and ideality factor of the device have been studied. The current–voltage and conductance–voltage characteristics are found largely sensitive to the parameters controlling the distribution profile of interface states. A new expression for the ideality factor of the device has been derived, which predicts appreciable voltage dependence due to the distributive nature of the interface states. It has been found that the experimental I– V data of p-InP/n-CdS heterojunction reported by earlier workers can be satisfactorily explained with the help of the present model if the effect of shunt resistance of the device is included in the evaluation scheme.

Keywords: Interface states; Semiconductor heterojunction diode

Investigation of SiO₂/Si₃N₄ films prepared on sapphire by r.f. magnetron reactive sputtering by Liping Feng; Zhengtang Liu; Qiang Li; Wenyan Song (pp. 4064-4070).

Sapphire is a desired material for infrared-transmitting windows and domes because of its excellent optical and mechanical properties. However, its thermal shock resistance is limited by loss of compressive strength along the c-axis of the crystal with increasing temperature. In this paper, double layer films of SiO₂/Si₃N₄ were prepared on sapphire (α-Al₂O₃) by radio frequency magnetron reactive sputtering in order to increase both transmission and high temperature mechanical performance of infrared windows of sapphire. Composition and structure of each layer of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. Surface morphology and roughness of coated and uncoated sapphire have been measured using a talysurf. Flexural strengths of sapphire sample uncoated and coated with SiO₂/Si₃N₄ have been studied by 3-point bending tests at different temperatures. The results show that SiO₂/Si₃N₄ films can improve the surface morphology and reduce the surface roughness of sapphire substrate. In addition, the designed SiO₂/Si₃N₄ films can increase the transmission of sapphire in mid-wave infrared and strengthen sapphire at high temperatures. Results for 3-point bending tests indicated that the SiO₂/Si₃N₄ films increased the flexural strength of c-axis sapphire by a factor of about 1.4 at 800°C.

Keywords: PACS; 68.35.Ct; 78.30.−j; 81.15.Cd; 81.65.−bMagnetron sputtering; SiO; ₂; /Si; ₃; N; ₄; films; Sapphire; Transmission; Flexural strength

Magnesia formed on calcination of Mg(OH)₂ prepared from natural bischofite by I.F. Mironyuk; V.M. Gun’ko; M.O. Povazhnyak; V.I. Zarko; V.M. Chelyadin; R. Leboda; J. Skubiszewska-Zięba; W. Janusz (pp. 4071-4082).

Calcination of magnesium hydroxide, which was prepared from natural bischofite MgCl₂·6H₂O, leading to dehydration 2(MgOH)→MgOMg+H₂O, is accompanied by transition of phase not only to MgO but also to MgO_x at x<1 (assigned to Mg₄O₃) at moderate temperatures. At higher temperatures, MgO_x is completely transformed into MgO. Magnesium hydroxide and oxide heated at different temperatures were studied using the TEM, XRD, IR, PCS, TG-DTA, nitrogen and argon adsorption methods. The electronic structure of MgO and Mg₄O₃ was studied using the ab initio quantum chemical method with periodic conditions. According to TEM images, the morphology of particles changing from Mg(OH)₂ laminae to aggregates of interpenetrated MgO cubelets and foils depend strongly on the calcination temperature. Significant changes in surface area are observed mainly at 325–470°C on desorption of a major portion of eliminated water corresponding to 28.4wt.% at its total amount of 30.9wt.%. Pore size distribution (PSD) is sensitive to treatment conditions and the main PSD peaks shift towards larger pore size with elevating temperature. The characteristics of the surface hydroxyls as well as of the bulk MgO bonds depend on heating conditions, as noticeable changes are observed in the XRD patterns and the IR spectra of the samples undergoing the mentioned transformation of phase Mg(OH)₂→MgO_x→MgO.

Keywords: Bischofite; Magnesium hydroxide; Magnesia; MgO; _x; TEM; XRD; IR; PCS; TG-DTA; Argon adsorption; Nitrogen adsorption; Periodic ab initio calculation; Water desorption; Transition of phase; Particle morphology; Surface hydroxyls

Morphological characteristics of amorphous Ge₂Sb₂Te₅ films after a single femtosecond laser pulse irradiation by Guangjun Zhang; Donghong Gu; Xiongwei Jiang; Qingxi Chen; Fuxi Gan (pp. 4083-4090).

The morphology of materials resulting from laser irradiation of the single-layer and the multilayer amorphous Ge₂Sb₂Te₅ films using 120fs pulses at 800nm was observed using scanning electron microscopy and atomic force microscopy. For the single-layer film, the center of the irradiated spot is depression and the border is protrusion, however, for the multilayer film, the center morphology changes from a depression to a protrusion as the increase of the energy. The crystallization threshold fluence of the single-layer and the multilayer film is 22 and 23mJ/cm², respectively.

Keywords: PACS; 79.20.D; 78.55.Q; 68.37.E; 68.37.PFemtosecond laser; Amorphous materials; Scanning electron microscopy; Atomic force microscopy

Chemical bath deposition of hausmannite Mn₃O₄ thin films by Hai Yan Xu; Si Le Xu; Xu Dong Li; Hao Wang; Hui Yan (pp. 4091-4096).

A low-temperature chemical bath deposition (CBD) technique has been used for the preparation of Mn₃O₄ thin films onto glass substrates. The kinetic behavior and the formation mechanism of the solid thin films from the aqueous solution have been investigated. Structure (X-ray diffraction and Raman), morphological (atom force microscope), and optical (UV–vis–NIR) characterizations of the deposited films are presented. The results indicated that the deposited Mn₃O₄ thin films of smooth surface with nanosized grains were well crystalline and the optical bandgap of the film was estimated to be 2.54eV.

Keywords: Mn; ₃; O; ₄; Thin film; Chemical bath deposition

Adsorption of octadecyltrichlorosilane on mesoporous SBA-15 by S.A. Mirji; S.B. Halligudi; Dhanashri P. Sawant; Nalini E. Jacob; K.R. Patil; A.B. Gaikwad; S.D. Pradhan (pp. 4097-4103).

Adsorption of octadecyltrichlorosilane (OTS) on mesoporous SBA-15 has been studied by using Brunauer–Emmett–Teller (BET) surface area analysis, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analysis (TGA) techniques. BET surface area analysis shows decrease of surface area from 930 to 416m²/g after OTS adsorption. SEM pictures show close attachment of SBA-15 particles. EDAX measurements show increase of carbon weight percentage and decrease of oxygen and silicon weight percentage. XPS results closely support EDAX analysis. FTIR spectra shows presence of methyl (–CH₃) and methylene (–CH₂) bands and oriented OTS monolayer on SBA-15. Thermo-gravimetric analysis shows that the OTS adsorbed on SBA-15 are stable up to a temperature of 230°C and that the OTS monolayers decompose between 230 and 400°C.

Keywords: PACS; 68.18.−g; 68.43.−h; 68.47.Pe; 81.16.DnSBA-15; OTS; Self-assembly; Adsorption; Thermal stability

The effect of Be-doping structure in negative electron affinity GaAs photocathodes on integrated photosensitivity by X.F. Wang; Y.P. Zeng; B.Q. Wang; Z.P. Zhu; X.Q. Du; M. Li; B.K. Chang (pp. 4104-4109).

A new structure of GaAs photocathode was introduced. The Be-doping concentration is variable in the new structure compared with the constant concentration of Be in the normal photocathode. Negative electron affinity GaAs photocathodes were fabricated by alternate input of Cs and O. The spectral response results measured by the on-line spectral response measurement system show that the integrated photosensitivity of the photocathodes with the new structure is enhanced by at least 50% as compared to those with the monolayer structure. Accordingly, two main factors leading to the enhanced photosensitivity of the photocathodes were discussed.

Keywords: PACS; 78.30.Fs; 79.60.Dp; 68.55.JKStructure; NEA; Integrated photosensitivity; GaAs; Cs:O

Femtosecond laser ablation of carbon reinforced polymers by P. Moreno; C. Méndez; A. García; I. Arias; L. Roso (pp. 4110-4119).

Interaction of intense ultrashort laser pulses (120 fs at 795 nm) with polymer based composites has been investigated. We have found that carbon filled polymers exhibit different ultrafast ablation behaviour depending on whether the filling material is carbon black or carbon fiber and on the polymer matrix itself. The shape and dimensions of the filling material are responsible for some geometrical bad quality effects in the entrance and inner surfaces of drilled microholes. We give an explanation for these non-quality effects in terms of fundamentals of ultrafast ablation process, specifically threshold laser fluences and material removal paths. Since carbon fiber reinforced polymers seemed particularly concerned, this could prevent the use of ultrafast ablation for microprocessing purposes of some of these materials.

Keywords: PACS; 79.20.Ds; 42.62.Cf; 61.82.Pv; 78.66.Sq; 81.05.QkFemtosecond laser ablation; Carbon reinforced polymers; Polyetheretherkethone; Perfluoroalkoxy

Experimental and theoretical study for corrosion inhibition of mild steel in hydrochloric acid solution by some new hydrazine carbodithioic acid derivatives by K.F. Khaled (pp. 4120-4128).

The corrosion inhibition of mild steel in 0.5M hydrochloric acid solutions by some new hydrazine carbodithioic acid derivatives namely N′-furan-2-yl-methylene-hydrazine carbodithioic acid (A), N′-(4-dimethylamino-benzylidene)-hydrazine carbodithioic acid (B) and N′-(3-nitro-benzylidene)-hydrazine carbodithioic (C) was studied using chemical (weight loss) and electrochemical (potentiodynamic and electrochemical impedance spectroscopy, EIS) measurements. These measurements show that the inhibition efficiency obtained by these compounds increased by increasing their concentration. The inhibition efficiency follow the order C>B>A. Polarization studies show that these compounds act as mixed type inhibitors in 0.5M HCl solutions. These inhibitors function through adsorption following Langmuir isotherm. The electronic properties of these inhibitors, obtained using PM3 semi-empirical self-consistence field method, have been correlated with their experimental efficiencies using non-linear regression method.

Keywords: Mild steel; Acid corrosion inhibitors; PM3 quantum method; EIS; Acid corrosion inhibition

In situ monitoring of bare and K-doped Mo₂C catalysts surface depassivation based on emission of electrons and K⁺ ions by Andrzej Kotarba; Grzegorz Adamski; Zbigniew Sojka; Gerald Djega-Mariadassou; Jan B.C. Pettersson (pp. 4129-4137).

The method for in situ characterization of surface transformations on heterogeneous catalyst is described. The method is based on the measurements of thermal electron and ion emissions from the catalyst surface. It is demonstrated by investigating the depassivation process of undoped and K-doped Mo₂C catalysts exposed to air after synthesis and use to identify characteristic steps of reduction-carburization by flowing CH₄/H₂ gas mixture. The information obtained from thermal emission experiments is consistent with the methane consumption profile, which provided an independent observation of the recarburization step.

Keywords: Mo; ₂; C catalyst; Depassivation; Electron emission; Work function; Potassium desorption; In situ monitoring

Temperature effect on deposition rate of silicon nitride films by Byungwhan Kim; Jae Young Park; Kyeong Kyun Lee; Jeon Gun Han (pp. 4138-4145).

Temperature effects on deposition rate of silicon nitride films were characterized by building a neural network prediction model. The silicon nitride films were deposited by using a plasma enhanced chemical vapor deposition system and process parameter effects were systematically characterized by 2⁶⁻¹ fractional factorial experiment. The process parameters involved include a radio frequency power, pressure, temperature, SiH₄, N₂, and NH₃ flow rates. The prediction performance of generalized regression neural network was drastically improved by optimizing multi-valued training factors using a genetic algorithm. Several 3D plots were generated to investigate parameter effects at various temperatures. Predicted variations were experimentally validated. The temperature effect on the deposition rate was a complex function of parameters but N₂ flow rate. Larger decreases in the deposition rate with the temperature were only noticed at lower SiH₄ (or higher NH₃) flow rates. Typical effects of SiH₄ or NH₃ flow rate were only observed at higher or lower temperatures. A comparison with the refractive index model facilitated a selective choice of either SiH₄ or NH₃ for process optimization.

Keywords: Model; Generalized regression neural network; Genetic algorithm; Statistical experimental design; Silicon nitride film; Deposition rate; Substrate temperature

Interband transitions and electronic properties of InAs/GaAs quantum dots embedded in Al_xGa1−_xAs/GaAs modulation-doped heterostructures by H.C. Im; J.H. Kim; D.H. Oh; T.W. Kim; K.H. Yoo; M.D. Kim (pp. 4146-4153).

Reflection high-energy electron diffraction, atomic force microscopy, transmission electron microscopy, and double-crystal X-ray curves showed that high-quality InAs quantum dot (QD) arrays inserted into GaAs barriers were embedded in an Al_0.3Ga_0.7As/GaAs heterostructure. The temperature-dependent photoluminescence (PL) spectra of the InAs/GaAs QDs showed that the exciton peak corresponding interband transition from the ground electronic subband to the ground heavy-hole subband (E₁–HH₁) was dominantly observed and that the peak position and the full width at half maximum corresponding to the interband transitions of the PL spectrum were dependent on the temperature. The activation energy of the electrons confined in the InAs/GaAs QDs was 115meV. The electronic subband energy and the energy wave function of the Al_0.3Ga_0.7As/GaAs heterostructures were calculated by using a self-consistent method. The electronic subband energies in the InAs/GaAs QDs were calculated by using a three-dimensional spatial plane wave method, and the value of the calculated (E₁–HH₁) transition in the InAs/GaAs QDs was in reasonable agreement with that obtained from the PL measurement.

Keywords: InAs/GaAs quantum dot; Interband transition; Activation energy

Surface-modified antibacterial TiO₂/Ag⁺ nanoparticles: Preparation and properties by Qilin Cheng; Chunzhong Li; Vladimir Pavlinek; Petr Saha; Huanbing Wang (pp. 4154-4160).

Studies were performed on surface modification of antibacterial TiO₂/Ag⁺ nanoparticles by grafting γ-aminopropyltriethoxysilane (APS). The interfacial structure of the modified particles was characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and thermogravimetric analysis. The thickness of the surface layer was determined by using Auger electron spectroscopy (AES). The results show that APS is chemically bonded to the surface of antibacterial TiO₂/Ag⁺ nanoparticles. Furthermore, the modified particles were mixed in PVC to prepare composites whose antibacterial property was investigated. The results suggest that surface modification has no negative effect on antibacterial activity of TiO₂/Ag⁺ nanoparticles and PVC–TiO₂/Ag⁺ composites exhibits good antibacterial property.

Keywords: TiO; ₂; /Ag; ⁺; nanoparticles; Surface modification; APS; Antibacterial property

Improvement of photoluminescence properties of porous silicon by silica passivation by Xi-Wen Du; Ying-Wei Lu; Jun-Peng Liu; Jing Sun (pp. 4161-4166).

Porous silicon (PS) was passivated by silica film using a sol–gel method; the photoluminescence (PL) properties were significantly improved; namely, PL intensity and stability increased and PL peak shifted to shorter wavelength. Scanning electron microscope (SEM) and Fourier transformed infrared spectroscope (FTIR) results indicated that silica passivation produced a compact film on the PS surface and modified the surface state of PS. The number of stable surface bonds (HSiO₃, HSiSiO₂ and H₂SiO₂) increased due to the oxidation of SiH back-bonds during the gelation process, and thus the PL intensity and stability were improved. Moreover, the blue-shift of PL peak was determined due to the increase in the ratio of SiO/SiH.

Keywords: Anodic oxidation; Silicon oxide; Optical properties; Fourier transform infrared spectroscopy (FTIR)

Growth and oxidation of aluminum thin films deposited on Ag(1 1 1) by H. Oughaddou; S. Vizzini; B. Aufray; B. Ealet; J.-M. Gay; J.-P. Bibérian; F.A. d’Avitaya (pp. 4167-4170).

Auger electron spectroscopy (AES) and low energy electron diffraction (LEED) were used to study the first steps of growth and oxidation of aluminum on Ag(1 1 1) substrate. We find that the growth of aluminum at room temperature (RT) shows the formation of a complete monolayer (ML) in epitaxy with the substrate. After deposition at RT of one aluminum ML, the dissolution kinetics is recorded at 200°C and the bulk diffusion coefficient is deduced. We also show that the oxidation at RT of one aluminum ML is very rapid, and that both aluminum and oxygen do not dissolve in silver up to 500°C. From the AES intensities variations, we deduce the composition profile of the oxide layer which corresponds probably to the stacking…/Ag/Ag/Al/O.

The size effect of Ba_0.6Sr_0.4TiO₃ thin films on the ferroelectric properties by Hongwei Chen; Chuanren Yang; Chunlin Fu; Li Zhao; Zhiqiang Gao (pp. 4171-4177).

Barium strontium titanate (BST) thin films were prepared by RF magnetron sputtering. The dielectric constant–voltage curves and the hysteresis loops of BST thin films with different grain sizes and film thicknesses were investigated. When the grain size increases from 12nm to 35nm, remarkable increases in dielectric constant and tunability were observed. Above 12nm, the BST films exhibited size effects, i.e. a decrease in maximal polarization ( P_m) and an increase in coercive electric field ( E_c) with reduction in grain size. In our investigation, the dielectric constant, tunability and maximal polarization increased as the film thickness increased. Furthermore, the size dependence of the dielectric constant and tunability of Ba_0.6Sr_0.4TiO₃ thin films is determined by that of the maximal polarization and the coercive electric field.

Keywords: Barium strontium titanate; Thin film; Ferroelectric property; Grain size; Film thickness

Spinodal-like decomposition of InGaP epitaxial layers grown on GaP substrates by J. Novák; S. Hasenöhrl; I. Vávra; M. Ku�?era (pp. 4178-4184).

The spinodal-like decomposition of In_xGa1−_xP epitaxial layer prepared by low-pressure metallorganic vapour phase epitaxy was studied by means of photoluminescence and transmission electron microscopy. Epitaxial layers were grown on GaP substrates at T_g=740°C and reactor pressure of 20mbar. We show that presence of spinodal-like decomposition occur at samples with InP mole fraction higher as x=0.2 and V/III ratio of 75. The low-temperature photoluminescence spectra shows that in partially decomposed samples a characteristic broad band occurred close to 1.985eV. An increase in the V/III ratio up to a value of 350 suppressed the decomposition, and PL signal with only one narrow transition was obtained.

Keywords: Spinodal; Decomposition; MOVPE; Epitaxy; InGaP alloy

Preparation of boron carbon nitride thin films by radio frequency magnetron sputtering by Lihua Liu; Yuxin Wang; Kecheng Feng; Yingai Li; Weiqing Li; Chunhong Zhao; Yongnian Zhao (pp. 4185-4189).

Boron carbon nitride films were deposited by radio frequency magnetron sputtering using a composite target consisting of h-BN and graphite in an Ar–N₂ gas mixture. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The results suggest that the films are atomic-level hybrids composed of B, C and N atoms. The boron carbon nitride films prepared in the present experiment have a disordered structure. The sputtering power varied from 80W to 130W. This sputtering power was shown to have regular effect on the composition of boron carbon nitride films. The samples deposited at 80W and 130W are close to the stoichiometry of BC₃N. The sample deposited at 110W is close to the stoichiometry of BCN. The samples deposited at 100W and 120W approach to BC₂N. It is very significant for us to synthesize boron carbon nitride compound with controllable composition by changing the sputtering power.

Keywords: Radio frequency magnetron sputtering; Boron carbon nitride thin films

Establishment of equivalent circuits from electrochemical impedance spectroscopy study of corrosion inhibition of steel by pyrazine in sulphuric acidic solution by M. Kissi; M. Bouklah; B. Hammouti; M. Benkaddour (pp. 4190-4197).

This paper describes the use of the electrochemical impedance spectroscopy technique (EIS) in order to study the corrosion inhibition process of steel in 0.5M H₂SO₄ solution at the open circuit potential (OCP). Diethyl pyrazine-2,3-dicarboxylate (Prz) as a non-ionic surfactant (NS) inhibitor has been examined. The Nyquist diagrams consisted of a capacitive semicircle at high frequencies followed by a well-defined inductive loop at low frequency values. The impedance measurements were interpreted according to suitable equivalent circuits. The results obtained showed that the Prz is a good inhibitor. The inhibition efficiency increases with an increase in the surfactant concentration to attain 80% at the 5×10⁻³M. Prz is adsorbed on the steel surface according to a Langmuir isotherm adsorption model.

Keywords: Electrochemical impedance spectroscopy; Steel; Pyrazine; Inhibition; Corrosion; Sulphuric acid

Simulation and fabrication of carbon nanotubes field emission pressure sensors by Kaiyou Qian; Ting Chen; Bingyong Yan; Yangkui Lin; Dong Xu; Zhuo Sun; Bingchu Cai (pp. 4198-4201).

A novel field emission pressure sensor has been achieved utilizing carbon nanotubes (CNTs) as the electron source. The sensor consists of the anode sensing film fabricated by wet etching process and multi-wall carbon nanotubes (MWNTs) cathode in the micro-vacuum chamber. MWNTs on the silicon substrate were grown by thermal CVD. The prototype pressure sensor has a measured sensitivity of about 0.17–0.77nA/Pa (101–550KPa). The work shows the potential use of CNTs-based field-emitter in microsensors, such as accelerometers and tactile sensors.

Keywords: Carbon nanotubes; Field emission; Pressure sensors

The role of grain boundaries in the mechanism of plasma immersion hydrogenation of nanocrystalline magnesium films by L. Pranevicius; D. Milcius; L.L. Pranevicius; C. Templier; B. Bobrovaite; I. Barnackas (pp. 4202-4208).

In this paper, attention in focused on the nanostructured magnesium films for hydrogen storage. It is shown that 2μm thick Mg film is transformed into MgH₂ film under high-flux and fluence hydrogen plasma immersion ion implantation at 450K for 15min. All hydrogen desorbs at temperature about 530K, which corresponds to the decomposition of MgH₂→Mg+H₂↑. The macroscopic and microscopic observations show that magnesium film undergoes a high deformation and restructuring during hydrogenation–dehydrogenation reaction. The suggested hydrogenation model is based upon the incorporation of excess of hydrogen atoms in grain boundaries of nanocrystalline Mg film driven by the increase in surface chemical potential associated with the implantation flux. The results provide new aspects of hydriding of thin nanocrystalline film materials under highly non-equalibrium conditions on the surface.

Keywords: Mg films; Grain boundaries; Plasma immersion ion implantation; Hydrogen storage

Influence of oxidation time on semiconductive behaviour of thermally grown oxide films on AISI 304L by L. Hamadou; A. Kadri; D. Boughrara; N. Benbrahim; J.-P. Petit (pp. 4209-4217).

The oxide films formed on AISI 304L stainless steel at 300°C in the oxidation time range between 2 and 4h have been studied by photoelectrochemistry. Photocurrents were investigated as a function of the wavelength of the incident light and the electrode potential. The investigation allowed the determination of the semiconductive properties of the oxides. The oxide films showed n-type behaviour. A duplex structure of the oxide films has been suggested on the basis of the photocurrent spectra, with an internal oxide layer having an optical gap ( E_g2=2.16–2.3eV) depending on the applied potential and oxidation time, higher to that of the external oxide layer ( E_g1≈1.9eV). Significant variations in the amplitude of the photocurrent were detected as a function of the applied potential and the oxidation time.

Keywords: 304L stainless steel; Photocurrent; Oxide films

Formation and characterization of conductive thin layers of copper sulfide (Cu_xS) on the surface of polyethylene and polyamide by the use of higher polythionic acids by Ingrida Ancutiene; Vitalijus Janickis; Remigijus Ivanauskas (pp. 4218-4225).

Layers of copper sulfide of varying composition and properties are formed on the surface of polyethylene and polyamide by a sorption–diffusion method using solutions of higher polythionic acids, H₂S_nO₆. The concentration of sulfur adsorbed–diffused into PE and PA depends on the degree of the acid sulfurity, n, the temperature of the solution and the period of the polymer treatment. The amount of copper in a sulfide (Cu_xS) layer formed after the sulfured polymer treatment with a solution of Cu(I–II) salt is strongly dependent on the concentration of sulfur in the PE and PA. By the chemical analysis of the obtained sulfide layers was determined that a value of x in the Cu_xS layers varies in the interval 1< x<2. The microscopic investigation of transverse sections of PE and PA samples with copper sulfide layers showed that the major part of copper sulfide is in the surface matrix of the polymer. X-ray diffraction studies of the Cu_xS layers obtained seven phases: with x=2 (chalcocite), 1.9375 (djurleite), 1.8 (digenite), 1.75 (anilite), 1.12 (yarrowite), 1.06 (talnakhite) and 1 (covellite). The measurements of the electrical conductance of Cu_xS layers (0.1–4Scm⁻²) showed that its value greatly depends on the conditions of PE and PA interaction with H₂S_nO₆ and of further interaction with Cu(I–II) salt solution, on the chemical and phase composition of the layer.

Keywords: Polyamide; Polyethylene; Polythionic acid; Copper sulfide; Conductive layer

Terahertz dichroism of MBBA liquid crystal on rubbed substrate by Jun-ichi Nishizawa; Tetsuya Yamada; Tetsuo Sasaki; Tadao Tanabe; Toshimasa Wadayama; Takenori Tanno; Ken Suto (pp. 4226-4229).

Terahertz (THz) dichroism of a nematic liquid N-( p-methoxybenzylidene)- p-butylaniline (MBBA) was measured using a GaP Raman THz spectrometer. MBBA on a rubbed plastic substrate generates a band at around 4.0THz: its liquid crystal phase shows strong dichroism, which well corresponds to that of the IR absorption caused by π(CH) of MBBA molecule reported in the literature. Based on inferences drawn from the present THz and the published IR dichroic results, the 4.0THz band probably stems from lateral intermolecular or intramolecular interactions of MBBA molecules aligned to the rubbing direction. The results clearly demonstrate that THz spectroscopy is powerful for discussing of phase transition and dichroism of liquid crystals.

Keywords: Terahertz dichroism; MBBA; Liquid crystal (LC)

Pattern design in large area using octadecyltrichlorosilane self-assembled monolayers as resist material by Peng Jiang; Shun-Yu Li; Hiroyuki Sugimura; Osamu Takai (pp. 4230-4235).

Various clean complicated micro-pattern designs based on n-octadecyltrichlorosilane (OTS) self-assembled monolayer (SAM) on silicon substrates have been realized in large area by using vacuum ultraviolet (VUV) light irradiation at the wavelength of 172nm. The degradation process of the alkylsilane SAM with irradiation time evolution has been traced by using ellipsometry, water contact angle measurement and X-ray photoelectron spectroscopy (XPS) techniques in detail. The results indicate that the SAM can be completely removed in several minutes by the irradiation of the shorter wavelength vacuum ultraviolet light. Furthermore, the ability of the OTS-SAM as resist for chemical etching has also been demonstrated.

Keywords: n; -Octadecyltrichlorosilane; Self-assembled monolayer; Vacuum ultraviolet (VUV) photolithography; Characterization

The study of ion mixed amorphous carbon films on single crystal silicon by C ion implantation by Rong Sun; Tao Xu; Jing-wei Zhang; Qun-ji Xue (pp. 4236-4243).

Amorphous-carbon (a-C) films were deposited on a single-crystal silicon substrate by vacuum vapor deposition system and these amorphous carbon films were implanted with 110keV C⁺ at fluences of 1×10¹⁷ions/cm². The effect of ion mixing on the surface morphology, friction behavior and adhesion strengths of amorphous carbon films was examined making use of atomic force microscopy (AFM), ball-on-disk reciprocating friction tester, nano-indentation system and scanning electron microscope (SEM). The changes in chemical composition and structure were investigated by using X-ray photoelectron spectroscopy (XPS). The results show that the anti-wear life and adhesion of amorphous carbon films on the Si substrates were significantly increased by C ion implantation. The SiC chemical bonding across the interface plays a key role in the increase of adhesion strength and the anti-wear life of amorphous carbon film. The friction and wear mechanisms of amorphous carbon film under dry friction condition were also discussed.

Keywords: Amorphous carbon film; C; ⁺; implantation; Single-crystal silicon; Friction and wear

Influence of preparation technology on the microstructure and anti-oxidation property of SiC–Al₂O₃–mullite multi-coatings for carbon/carbon composites by Jian-Feng Huang; He-Jun Li; Xie-Rong Zeng; Xin-Bo Xiong; Ke-Zhi Li (pp. 4244-4249).

Oxidation protective SiC–Al₂O₃–mullite multi-coatings for carbon/carbon (C/C) composites were prepared with a two-step pack cementation process. The influence of preparation temperature and SiO₂/Al₂O₃ ratio of the pack powder on the phase, microstructure and oxidation resistance of the multi-coatings were investigated. It showed that the multi-coatings that contained mullite could be produced at 1700–1800°C. A denser coating surface was acquired with the decrease of SiO₂/Al₂O₃ ratio in the pack chemistries while a little damnification to the interface of the coating and C/C substrate. The as-prepared coating could effectively protect C/C composites from oxidation at 1600°C for 81h.

Keywords: Carbon/carbon composites; Coating; Oxidation; Surface structure, morphology, roughness and topography; X-ray scattering; Diffraction; Reflection; Solid surfaces and solid interfaces

XPS study of porous dental implants fabricated by electro-discharge-sintering of spherical Ti–6Al–4V powders in a vacuum atmosphere by W.H. Lee; C.Y. Hyun (pp. 4250-4256).

A single electro-discharge-sintering (EDS) pulse (0.7–2.0kJ/0.7g), from a 300μF capacitor, was applied to atomized spherical Ti–6Al–4V powder in a vacuum to produce a porous-surfaced implant compact. A solid core surrounded by a porous layer was formed by a discharge in the middle of the compact. X-ray photoelectron spectroscopy was used to study the surface characteristics of the implant material. C, O, and Ti were the main constituents, with smaller amounts of Al, V, and N. The implant surface was lightly oxidized and was primarily in the form of TiO₂ with a small amount of metallic Ti. A lightly etched EDS implant sample showed the surface form of metallic Ti, indicating that EDS breaks down the oxide film of the as-received Ti–6Al–4V powder during the discharge process. The EDS Ti–6Al–4V implant surface also contained small amounts of aluminum oxide in addition to TiO₂. However, V detected in the EDS Ti–6Al–4V implant surface did not contribute to the formation of the oxide film. The small amount of N in the implant surface resulted from nitride material that was also found in the as-received Ti–6Al–4V powders.

Keywords: PACS; 68.35.BTi–6Al–4V; Implant; XPS; Surface modification

The effects of pulsed Nd:YAG laser irradiation on surface energy of copper by Zhenqing Zhao; Chunqing Wang; Mingyu Li; Lei Wang; Lingchao Kong (pp. 4257-4263).

The effect of laser surface treatment on the surface energy of copper plate was investigated in terms of the surface microstructure analysis and theoretical computation in this paper. The surfaces of the copper plates were treated by Nd:YAG pulsed laser with different powers. The microstructures of the treated copper plates were analyzed by optical microscopy and X-ray diffraction (XRD), and the wetting experiment was performed to evaluate the variation of surface energy. The results showed that the surface microstructure and the corresponding surface energy of copper, changed with the variation of the laser power. The experimental results further explained by XRD results and theoretical calculation, demonstrated that the surface energy changed when the crystal structure in the surface layer was re-oriented in a preferred orientation after laser irradiation.

Keywords: Laser treatment; Copper; Surface energy; Crystal structure

Physical–morphological and chemical changes leading to an increase in adhesion between plasma treated polyester fibres and a rubber matrix by H. Krump; I. Hudec; M. Jaššo; E. Dayss; A.S. Luyt (pp. 4264-4278).

The effects of plasma treatment, used to increase adhesion strength between poly(ethylene terephtalate) (PET) fibres and a rubber matrix, were investigated and compared. Morphological changes as a result of atmospheric plasma treatment were observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Wettability analysis using a surface energy evaluation system (SEE system) suggested that the plasma treated fibre was more wetting towards a polar liquid. When treated, these fibres showed a new lamellar crystallization, as shown by a new melting peak using differential scanning calorimetry (DSC). X-ray photoelectron spectroscopy (XPS) has been used to study the chemical effect of inert (argon), active and reactive (nitrogen and oxygen) microwave-plasma treatments of a PET surface. Reactive oxygen plasma treatment by a de-convolution method shows new chemical species that drastically alter the chemical reactivity of the PET surface. These studies have also shown that the surface population of chemical species formed after microwave-plasma treatment is dependent on the plasma gas. All these changes cause better adhesion strength of the PET fibres to the rubber matrix.

Keywords: Plasma treatment; Scanning electron microscopy (SEM); Atomic force microscopy (AFM); Adhesion strength; Differential scanning calorimetry (DSC); X-ray photoelectron spectroscopy (XPS)

The assessment of metal surface cleanliness by XPS by C. Scheuerlein; M. Taborelli (pp. 4279-4288).

The most commonly used quantity to characterize surface cleanliness through X-ray photoemission spectroscopy (XPS) measurements is the so-called relative atomic surface concentration of carbon (at.%C). We have investigated the relationship between at.%C values and the C 1s peak area on Cu and we find a nearly linear behaviour in the range 15–80at.%C. Correction factors for the measured at.%C values that enable a comparison of the cleanliness level of different materials, notably Cu, Al and stainless steel, have been determined experimentally.The influence of the storage time and method on the degree of re-contamination of initially clean Cu has been examined. The carbon contamination on clean metallic Cu increases abruptly to some 20at.%C upon air exposure and continues to increase with storage time in air. Storage in polymer bags can lead to up to 70at.%C after 1 month, whereas storage in aluminium foil can preserve an acceptable surface cleanliness for a similar storage time.

Keywords: X-ray photoemission spectroscopy; Surface cleaning; Cleanliness

Surface chemical modification of TEOS based silica aerogels synthesized by two step (acid–base) sol–gel process by Sharad D. Bhagat; A. Venkateswara Rao (pp. 4289-4297).

The present paper describes the comparative studies on the hydrophobic and physical properties of the tetraethoxysilane (TEOS) based silica aerogels prepared by two step sol–gel process followed by supercritical drying. Silica alcogels were prepared by keeping the molar ratio of TEOS:methanol (MeOH):H₂O (acidic):H₂O (basic) constant at 1:33:3.5:3.5 with oxalic acid and ammonium hydroxide concentrations fixed at 0.001 and 1M, respectively. In all, nine different co-precursors (CP) of the type R_nSiX4−_n, have been used. The aerogels have been characterized by density, porosity, percentage of volume shrinkage, optical transmission, contact angle and thermal conductivity measurements. The surface chemical modification of silica aerogels was confirmed by the presence of CH and SiC peaks at 2900, 1450 and 840cm⁻¹, respectively, from the Fourier transform-infrared spectroscopy (FT-IR). The microstructure of the aerogels was studied using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. In addition to these studies, the stability of the hydrophobic aerogels against an organic impurity (methanol, in the present studies) in water has also been studied.

Keywords: Silica aerogels; Hydrophobicity; Thermal stability; SEM; TEM

CO sensor derived from mesostructured Au-doped SnO₂ thin film by Niranjan S. Ramgir; Young Kyu Hwang; Sung Hwa Jhung; Hey-Kyung Kim; Jin-Soo Hwang; Imtiaz S. Mulla; Jong-San Chang (pp. 4298-4305).

Pure and Au-doped mesostructured SnO₂ thin films were successfully prepared by using non-ionic surfactant Brij-58 (polyoxyethylene acyl ether) as organic template and tin tetrachloride and hydrogen tetrachloroaurate(III) trihydrate as inorganic precursor. Thin films were deposited onto the glass substrates at 450°C by simple spray pyrolysis technique. The novel mesostructured tin oxide thin films with different Au concentration exhibit highly selective response towards CO. The correlation of the Au incorporation in the mesostructure with particular morphology and gas sensing behavior is discussed using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET surface area and transmission electron microscopy (TEM) studies.

Keywords: Mesostructure; Au; SnO; ₂; CO; Spray pyrolysis; Gas sensors

Luminescent molecular hybrid system derived from 2-furancarboxylic acid and silylated monomer coordinated to rare earth ions by Yu-Long Sui; Bing Yan (pp. 4306-4311).

In this study, silica-based organic–inorganic hybrids were prepared by the sol–gel method. Tetraethoxysilane (abbreviated as TEOS) and a kind of monomer (abbreviated as FA-APES) derived from modified 2-furancarboxylic acid (abbreviated as FA) with (3-aminopropyl)triethoxysilane (abbreviated as APES) were used as the inorganic and organic fragments, respectively. Coordination reaction between lanthanides (europium and terbium ions) andCO group of the monomer happened simultaneously. And after days of aging process the resultant materials showed characteristic luminescence of lanthanides. The enhancement of luminescence can be seen by the comparison with simply doped lanthanide hybrid systems. And it can be explained by the coordination ability of the organic counterpart. IR, NMR, UV–vis absorption, low-temperature phosphorescence spectroscopy and fluorescence spectroscopy were applied to characterize and the above spectroscopic data revealed that the triplet state energy of organic ligand matches with the emissive energy level of lanthanides (especially of Tb³⁺).

Keywords: Molecular hybrids; Bridge molecule; Double chemical bond; Terbium; Europium; Luminescence; 2-Furancarboxylic acid

Monolayer characteristics of stereoregular PMMA at the air/water interface by Wen-Ping Hsu; Yuh-Lang Lee; Shu-Hua Liou (pp. 4312-4320).

Behaviors of isotactic, atactic and syndiotactic poly(methyl methacrylate) (PMMA) monolayers at the air/water interface were investigated. The monolayer characteristics of the three stereoisomers were studied and compared in terms of surface pressure–area per molecule ( π– A) isotherm, hysteresis and relaxation phenomena, and the phase images observed from Brewster angle microscopy (BAM). The results show that iPMMA monolayer has a more extended and compressible property, and exhibits pronounced hysteresis and relaxation phenomena among the three tactic PMMAs. Such characteristics can reasonably be attributed to the higher flexibility of chains segments of iPMMA as estimated from its lower T_g. On the other hand, sPMMA, the one with the highest T_g, forms a more condensed monolayer due to the high cohesive interaction among polymer chains. The BAM images show that PMMA molecules are not well extended on the subphase and thus, aggregative phases were observed even in a state corresponding to the gas phase. The aggregative structures are especially significant on sPMMA monolayer, which is consistent with the results estimated from the π– A isotherms. When the temperature is elevated from 25 to 40°C, all the monolayers of the three stereoisomers become more expanded and compressible due to the increase in chain flexibility.

Keywords: Langmuir monolayer; Isotherm; Hysteresis; Relaxation; Brewster angle microscopy

Effect of temperature on pulsed laser deposition of ZnO films by M. Liu; X.Q. Wei; Z.G. Zhang; G. Sun; C.S. Chen; C.S. Xue; H.Z. Zhuang; B.Y. Man (pp. 4321-4326).

ZnO thin films have been deposited on Si(111) substrates at different substrate temperature by pulsed laser deposition (PLD) of ZnO target in oxygen atmosphere. An Nd:YAG pulsed laser with a wavelength of 1064nm was used as laser source. The influences of the deposition temperature on the thickness, crystallinity, surface morphology and optical properties of ZnO films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED), photoluminescence (PL) spectrum and infrared spectrum. The results show that in our experimental conditions, the ZnO thin films deposited at 400°C have the best surface morphology and crystalline quality. And the PL spectrum with the strongest ultraviolet (UV) peak and blue peak is observed in this condition.

Keywords: PLD; ZnO films; Temperature effects; Crystal structure; Optical properties

Inhibition effect of self-assembled films formed by gold nanoparticles on iron surface by Hongfang Ma; Shenhao Chen; Guangzeng Liu; Jing Xu; Min Zhou (pp. 4327-4334).

The self-assembled (SA) films formed by gold nanoparticles on iron surface had been proved to have inhibition effect for the substrate in 0.5M H₂SO₄ solutions. The inhibition action was investigated using electrochemical impedance spectroscopy (EIS). The SA films formed by gold nanoparticles protected with sodium oleate had better corrosion protection to the iron substrate than only by sodium oleate. Scanning electron microscopy (SEM) was used to observe the imagines of the SA films. In addition, it was found that the gold nanoparticles could influence the nickel electroless plating films on the iron substrate. The structure and composition of the plating films were test by electron probe microanalyzer (EPMA). The mechanisms of the formation of the SA films and the nickel electroless plating reaction were also discussed.

Keywords: Gold nanoparticles; Self-assembled films; Electrochemical impedance spectroscopy (EIS); Nickel electroless plating

Experimental and theoretical studies on X-ray induced secondary electron yields in Ti and TiO₂ by Takeshi Iyasu; Keiji Tamura; Ryuichi Shimizu; Mihai Aurel Vlaicu; Hideki Yoshikawa (pp. 4335-4339).

Generation of X-ray induced secondary electrons in Ti and TiO₂ was studied from both experimental and theoretical approaches, using X-ray photoelectron spectroscopy (XPS) attached to a synchrotron radiation facility and Monte Carlo simulation, respectively.The experiment revealed that the yields of secondary electrons induced by X-rays (electrons/photon) at photon energies to 4950 and 5000eV for Ti and TiO₂ are δ_Ti(4950eV)=0.002 and δ_Ti(5000eV)=0.014 while those for TiO₂ areδTiO2(4950eV)=0.003 andδTiO2(5000eV)=0.018.A novel approach to obtain the escape depth of secondary electrons has been proposed and applied to Ti and TiO₂. The approach agreed very well with the experimental data reported so far. The Monte Carlo simulation predicted;δTi*(4950eV)=0.002 andδTi*(5000eV)=0.011 whileδTiO2*(4950eV)=0.003 andδTiO2*(5000eV)=0.015.An experimental examination on the contribution of X-ray induced secondary electrons to photocatalysis in TiO₂ has also been proposed.

Keywords: PACS; 32.80.Fb; 34.80.Bm; 79.20.Hx; 79.20.Ap; 79.90.+bEscape depth; Monte Carlo simulation; TiO; ₂; X-ray induced secondary electrons

Initial study on the structure and photoluminescence properties of SiC films doped with Al by Z.D. Sha; X.M. Wu; L.J. Zhuge (pp. 4340-4344).

SiC films doped with aluminum (Al) were prepared by the rf-magnetron sputtering technique on p-Si substrates with a composite target of a single crystalline SiC containing several Al pieces on the surface. The as-deposited films were annealed in the temperature range of 400–800°C under nitrogen ambient. The thin films have been characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the introduction of Al into films hinders crystalline formation process. And with the increase of annealing temperature, more Si particles are formed in the films, which strongly affect the optical absorption properties. The photoluminescence (PL) spectra of the samples show two peaks at 370nm and 412nm. The intensities of the PL peaks are evidently improved after Al doped. We attribute the origin of the two PL peaks to a kind of Si-related defect centres. The obtained results are expected to have important applications in modern optoelectronic devices.

Keywords: PACS; 78.66.−w; 78.68.+m; 78.55.−m; 78.40.−qSiC films doped with Al; Structure; Annealing temperature; Photoluminescence

Adsorption energy distribution in activated carbon from grand canonical Monte Carlo calculation by G. Calleja; B. Coto; A.M. Morales-Cas (pp. 4345-4352).

The adsorption energy heterogeneity was studied by simulation using the Grand Canonical Monte Carlo method and the slit pore geometry. Nitrogen adsorption was simulated at 77K in pore sizes ranging from 0.46 to 2.06nm. The microscopic description of the adsorption phenomena is shown in terms of the density profile and the energy distribution function.Relation between the shape of the isotherm curve and the corresponding density profile has been discussed according to an odd or even number of layers inside the pore. Pore size distribution (PSD) for a commercial-activated carbon was calculated comparing experimental and simulated adsorption isotherm data.The energy distribution function was obtained for the pore size range above mentioned and was compared with the corresponding adsorption potential distribution. PSD obtained from experimental isotherm is combined with the energy distribution functions to propose a total energy distribution function for this material.

Keywords: PACS; 05.10.Ln; 68.35.Md; 05.70.NpNitrogen adsorption isotherms; Molecular simulation; Activated carbon; Energy distribution function; Energetic heterogeneity

Determination of phosphorus contamination during antimony implantation by measurement and simulation by M. Kuruc; L. Hulényi; R. Kinder (pp. 4353-4357).

Experimental determination of phosphorus cross-contamination during antimony implantation is presented. As a suitable structure for this experiment, a buried layer was employed which is created by implanting antimony followed by a long diffusion process. The samples implanted in different implanters were analysed by secondary ion mass spectrometry (SIMS), four-point probe and spreading resistance methods. The obtained results were compared with those calculated by program SUPREM-IV. Methods that can and cannot be used to determine phosphorus contamination during antimony implantation and to estimate the fluence of phosphorus being co-implanted with antimony are described in detail.

Keywords: Subject classification; 81.05.Ea; 84.37.+q; 85.40.RyImplantation; Doping profile; SIMS; Spreading resistance

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Applied Surface Science (v.252, #12)