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Applied Surface Science (v.256, #3)

Editorial Board (pp. ii).

Er³⁺ Doping conditions of planar porous silicon waveguides by A. Najar; N. Lorrain; H. Ajlani; J. Charrier; M. Oueslati; L. Haji (pp. 581-586).

EDX and infrared photoluminescence (IR PL) analyses performed on erbium-doped porous silicon waveguides (PSWG) were studied using different doping conditions. Both parameters of the cathodisation electrochemical method used for Er incorporation and parameters of thermal treatments required for Er optical activation were taken into consideration. Firstly, by varying the current density and the time of cathodisation, we have shown that a current density of 0.1mA/cm² for 10min allows homogeneous Er doping to be achieved throughout the depth of the guiding layer. Then, the PL intensity at 1.53μm was studied as a function of the oxidation time at 900°C and Er diffusion temperature for 60min. Increasing the oxidation time up to 1h allows PL to be enhanced due to active Si–O–Er complex formation whereas an oxidation time of 2h induces a decrease in PL because of Er segregation. Moreover, an increase in the diffusion temperature induces an optimal distribution of optically active Si–Er–O complexes inside the crystallites. When the temperature is too high, a PSWG densification and Er segregation occurs inducing a decrease in PL due to energy transfer phenomena.

Keywords: Porous silicon; Er doping; Waveguides; EDX; IR photoluminescence

Er³⁺ Doping conditions of planar porous silicon waveguides by A. Najar; N. Lorrain; H. Ajlani; J. Charrier; M. Oueslati; L. Haji (pp. 581-586).

Keywords: Porous silicon; Er doping; Waveguides; EDX; IR photoluminescence

Pore structure analysis on activated carbon fibers—By cluster and watershed transform method by Yu Zhu; Tian Zuo; Linjia Jiang; Zetian Cai; Cheng Yan; Xu Liu; Xing Malcolm; Qilin Wu (pp. 587-592).

The microimage of activated carbon fibers (ACFs) obtained from SEM or TEM has low signal to noise ratio (SNR). And the objects in image overlapped together. Image processing methods based on clustering analysis and watershed transform were applied to explore the macropores morphology structure of ACFs. The microimage shows that abundant round-shaped macropores with pore size around 50–200nm, some of which cluster in the form of ring, distribute on ACF surface. Through clustering analysis, we calculated the surface area of macropores and their distributions. The results showed that the pores characterize within three regions, (1) the pore objects smaller than 30 pixels distributing nearly uniformly; (2) those with pixels between 30 and 165 peaking at lower region and (3) those larger than 165 pixels having fewer numbers and provide the main part of clusters. According to watershed transform segmentation analysis, the overlapped pores in one cluster were separated from each other. The number and other morphology parameters of macropores are calculated automatically and accurately in this paper.

Keywords: ACF; SEM; Pore; Image processing; Clustering analysis; Watershed transform

A measurement of elastic moduli for tungsten films on polymer substrate using wrinkling analysis by Myoung-Woon Moon; Jun Hyun Han (pp. 593-596).

The elastic moduli of ultra thin tungsten (W) films on polymers were assessed with wrinkling analysis. Thin W films with a range of thickness between 17 and 100nm were deposited on compliant polymers and Si strips using DC magnetron sputtering method, causing the tensile stress in a few GPa scale with respect to the thickness of W films. By applying lateral compression on polymer, wrinkle patterns were developed in the W thin film with well-defined amplitude and wavelength. Using a simple equation on wrinkle analysis, the range of elastic moduli was estimated with increasing the thickness. It was found that the elastic modulus and the tensile stress decreased with increasing the film thickness.

Keywords: Wrinkling; Tungsten; Microstructure; DC magnetron sputtering

A measurement of elastic moduli for tungsten films on polymer substrate using wrinkling analysis by Myoung-Woon Moon; Jun Hyun Han (pp. 593-596).

Keywords: Wrinkling; Tungsten; Microstructure; DC magnetron sputtering

Synthesis, characterization and photocatalytic activities of rare earth-loaded BiVO₄ catalysts by Hui Xu; Chundu Wu; Huaming Li; Jinyu Chu; Guangsong Sun; Yuanguo Xu; Yongsheng Yan (pp. 597-602).

The BiVO₄-based photocatalysts loaded with rare earth (RE=Ho, Sm, Yb, Eu, Gd, Nd, Ce and La) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), nitrogen adsorption for the BET specific surface area and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by decolorization of methylene blue (MB) under visible light irradiation. The results of XRD, SEM and XPS analysis deduced that the rare earth ions were present as RE₂O₃ in the samples. The DRS analysis showed the shift in the absorbption edge from the UV to the visible range: Ho³⁺-BiVO₄3+-BiVO₄3+-BiVO₄3+-BiVO₄3+-BiVO₄3+-BiVO₄3+-BiVO₄3+-BiVO₄4. Gd³⁺-BiVO₄ had the highest photocatalytic activity among all the RE³⁺-BiVO₄ catalysts. The optimal Gd content was 8at% under visible light irradiation. This beneficial effect was attributed to the specific electron structure characteristics of gadolinium and the increasing in the separation efficiency of the electron–hole pairs. On the contrast, the other rare earth ions had the detrimental effect on the photocatalytic decolorization of MB.

Keywords: Rare earth; BiVO; ₄; Photocatalytic; Methylene blue; Visible light irradiation

Synthesis, characterization and photocatalytic activities of rare earth-loaded BiVO₄ catalysts by Hui Xu; Chundu Wu; Huaming Li; Jinyu Chu; Guangsong Sun; Yuanguo Xu; Yongsheng Yan (pp. 597-602).

Keywords: Rare earth; BiVO; ₄; Photocatalytic; Methylene blue; Visible light irradiation

Microstructure and discharge properties of Mg–Zr–O protective films in plasma display panel by Jianfeng Wang; Huiyan Wu; Zhongxiao Song; Kewei Xu; Chunliang Liu (pp. 603-607).

Mg–Zr–O protective films for plasma display panels (PDPs) were deposited on soda-lime glass substrates by magnetron sputtering method. The effects of Zr doping on both the discharge properties (firing voltage, V_f and the minimum sustaining voltage, V_s) and the microstructure of the Mg–Zr–O films were investigated. The results show that the deposited Mg–Zr–O films retain the NaCl-type structure as the pure MgO crystal. The doped Zr exists in the form of Zr⁴⁺ substitution solution in MgO crystal and an appropriate amount of Zr can improve the surface characteristics of the Mg–Zr–O films effectively. When the Zr atomic concentration is about 2%, the Mg–Zr–O films have the strongest (200) preferred orientation and the minimum surface roughness. The firing voltage and the minimum sustaining voltage of Mg–Zr–O protective layer are reduced at most by about 25V and 15V, respectively, compared with those of the pure MgO film. Mg–Zr–O protective layers with an appropriate amount of Zr are promising to meet the demands of advanced high-vision PDPs.

Keywords: Plasma display panel; Mg–Zr–O film; Magnetron sputtering; Microstructure; Discharge

Microstructure and discharge properties of Mg–Zr–O protective films in plasma display panel by Jianfeng Wang; Huiyan Wu; Zhongxiao Song; Kewei Xu; Chunliang Liu (pp. 603-607).

Keywords: Plasma display panel; Mg–Zr–O film; Magnetron sputtering; Microstructure; Discharge

Effect of deposition parameters on structural, optical and electrical properties of nanocrystalline ZnSe thin films by Charita Mehta; G.S.S. Saini; Jasim M. Abbas; S.K. Tripathi (pp. 608-614).

This paper presents the chemical bath deposition of zinc selenide (n-ZnSe) nanocrystalline thin films on non-conducting glass substrates, in an aqueous alkaline medium using sodium selenosulphate as Se²⁻ ion source. The X-ray diffraction studies show that the deposited ZnSe material is nanocrystalline with a mixture of hexagonal and cubic phase. The direct optical band gap ‘ E_g’ for the as-deposited n-ZnSe films is found to be 3.5eV. TEM studies show that the ZnSe nanocrystals (NCs) are spherical in shape. Formation of ZnSe has been confirmed with the help of infrared (IR) spectroscopy by observing bands corresponding to the multiphonon absorption. We demonstrate the effect of the deposition temperature and reactant concentration on the structural, optical and electrical properties of ZnSe films.

Keywords: PACS; Hf; 78.20.CiNanocrystals; Chemical bath deposition; Band gap; X-ray diffraction; Optical properties; Electrical properties

Effect of deposition parameters on structural, optical and electrical properties of nanocrystalline ZnSe thin films by Charita Mehta; G.S.S. Saini; Jasim M. Abbas; S.K. Tripathi (pp. 608-614).

Keywords: PACS; Hf; 78.20.CiNanocrystals; Chemical bath deposition; Band gap; X-ray diffraction; Optical properties; Electrical properties

Epitaxial growth of Nd₂Hf₂O₇(111) thin films on Ge(111) substrates by pulsed laser deposition by Feng Wei; Hailing Tu; Jun Du (pp. 615-618).

Nd₂Hf₂O₇ (NHO) thin films have been epitaxially grown by pulsed laser deposition (PLD) on Ge(111) substrates. In situ reflection high-energy electron diffraction (RHEED) evolution of the (111)-oriented NHO during the deposition has been investigated and shows that the epilayer has a twin-free character with type-B stacking. Interfacial structure of NHO/Ge has been examined by high-resolution transmission electron microscopy (HRTEM). The results indicate a highly crystalline film with a very thin interface, and the orientation relationship between NHO and Ge can be denoted as (111)_NHO//(111)_Ge and[1¯10]NHO//[11¯10]Ge. Finally, twin-free epitaxial growth of NHO with type-B orientation displays temperature dependence and the type-B epitaxy is favored at high temperature.

Keywords: PACS; 61.05.cp; 68.37.Og; 81.15.FgReflection high-energy electron diffraction; High-resolution transmission electron microscopy; Laser epitaxy; Dielectric materials

Epitaxial growth of Nd₂Hf₂O₇(111) thin films on Ge(111) substrates by pulsed laser deposition by Feng Wei; Hailing Tu; Jun Du (pp. 615-618).

Keywords: PACS; 61.05.cp; 68.37.Og; 81.15.FgReflection high-energy electron diffraction; High-resolution transmission electron microscopy; Laser epitaxy; Dielectric materials

Surface nanocrystallization mechanism of a rare earth magnesium alloy induced by HVOF supersonic microparticles bombarding by Kaidong Xu; Aihua Wang; Yang Wang; Xuanpu Dong; Xianglin Zhang; Zaowen Huang (pp. 619-626).

A nanostructured surface layer with a thickness up to 60μm was produced on a rare earth Mg–Gd–Y magnesium alloy using a new process named HVOF-SMB (high velocity oxygen-fuel flame supersonic microparticles bombarding). The microstructural features of the treated surface at various depth of the deformed layer were characterized by optical microscopy (OM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) with an aim to reveal the formation mechanism. Results showed that three steps during grain refinement process were found, i.e., twinning dominates the plastic deformation and divides the coarse grains into finer twin platelets at the initial stage, stacking faults are generated and a number of dislocation slip systems are activated leading to the cross slips with increasing strain and strain rate, eventually high-density dislocation networks, dislocation cells and dislocation arrays are formed, which further subdivides the twin platelets and residual microbands into sub-microstructures. As a result, homogeneous nanostructure with a grain size of about 10–20nm is formed through dynamic recrystallization in the topmost surface layer. Based on the experimental observations, a grain refinement mechanism induced by plastic deformation with higher strain rate during the HVOF-SMB treatment in the rare earth Mg–Gd–Y alloy was proposed.

Keywords: Rare earth Mg alloy; HVOF-SMB; Twinning; Dynamic recrystallization; Nano-grain size

Formation of p-type ZnMgO thin films by In–N codoping method by L. Gong; Z.Z. Ye; J.G. Lu; L.P. Zhu; J.Y. Huang; B.H. Zhao (pp. 627-630).

In–N codoped ZnMgO films have been prepared on glass substrates by direct current reactive magnetron sputtering. The p-type conduction could be obtained in ZnMgO films by adjusting the N₂O partial pressures. The lowest resistivity was found to be 4.6Ωcm for the p-type ZnMgO film deposited under an optimized N₂O partial pressure of 2.3mTorr, with a Hall mobility of 1.4cm²/Vs and a hole concentration of 9.6×10¹⁷cm⁻³ at room temperature. The films were of good crystal quality with a high c-axis orientation of wurtzite ZnO structure. The presence of In–N bonds was identified by X-ray photoelectron spectroscopy, which may enhance the nitrogen incorporation and respond for the realization of good p-type behavior in In–N codoped ZnMgO films. Furthermore, the ZnMgO-based p– n homojunction was fabricated by deposition of an In-doped n-type ZnMgO layer on an In–N codoped p-type ZnMgO layer. The p– n homostructural diode exhibits electrical rectification behavior of a typical p– n junction.

Keywords: PACS; 78.55.Et; 78.30.Fs; 73.61.Ga; 81.15.CdCharacterization; Doping; Physical vapor deposition; Oxides; Zinc compounds

Formation of p-type ZnMgO thin films by In–N codoping method by L. Gong; Z.Z. Ye; J.G. Lu; L.P. Zhu; J.Y. Huang; B.H. Zhao (pp. 627-630).

Keywords: PACS; 78.55.Et; 78.30.Fs; 73.61.Ga; 81.15.CdCharacterization; Doping; Physical vapor deposition; Oxides; Zinc compounds

Efficient and facile one pot carboxylation of multiwalled carbon nanotubes by using oxidation with ozone under mild conditions by Hossein Naeimi; Ali Mohajeri; Leila Moradi; Ali Morad Rashidi (pp. 631-635).

In this work, oxidation of carbon nanotubes with ozone in the presence of hydrogen peroxide was studied. The reactions were performed under clean and mild conditions and oxidized products with high concentration of oxygenated groups were yielded. The reaction products were characterized with attenuated total reflectance (ATR), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), back titration, X-ray photoelectron spectroscopy (XPS) and the dispersion behavior of the oxidized multiwalled carbon nanotubes (MWCNTs) was also studied. The results confirmed the presence of high concentrations of oxidative groups on the carbon nanotubes (CNTs) treated by the method of the present work.In this study, oxidation of carbon nanotubes with ozone in the presence of hydrogen peroxide was investigated. The reaction was performed under clean and mild conditions and oxidized products with high concentration of oxygenated groups were yielded. The reaction products were characterized with attenuated total reflectance (ATR), Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffractometry (XRD), back titration, X-ray photoelectron spectroscopy (XPS) and the dispersion behavior of the oxidized multiwalled carbon nanotubes (MWCNTs) was also studied. The results confirmed the presence of high concentrations of oxidative groups on the carbon nanotubes (CNTs) treated by the method of the present work.

Keywords: Multiwalled carbon nanotubes; Ozone; Hydrogen peroxide; Oxidation; Purification

Deduction of a three-phase model for the (√3×√3)R30°-Cu₂Si/Cu(111) surface alloy by I.G. Shuttleworth (pp. 636-639).

The (√3×√3)R30°-Cu₂Si/Cu(111) surface alloy that forms during high temperature dosing of silane (SiH₄) on Cu(111) has been investigated using LCAO–DFT. Simulated STM images have shown that experimental images may be interpreted as a mixed phase system consisting of Si ion cores bound in HCP, FCC and twofold bridge sites with a ratio of 25:25:50 rather than previously proposed models where the Si ion cores were bound in only FCC and HCP sites. The new model is shown to be consistent with previously published NIXSW studies.

Keywords: Cu; ₂; Si; Cu(1; 1; 1); Density functional theory (DFT); Linear combination of atomic orbitals (LCAO); Generalized gradient approximation (GGA); SIESTA; Scanning tunneling microscopy (STM); Normal incidence X-ray standing wave (NIXSW)

Deduction of a three-phase model for the (√3×√3)R30°-Cu₂Si/Cu(111) surface alloy by I.G. Shuttleworth (pp. 636-639).

The role of surface roughness in total internal reflection ellipsometry of hybrid systems by Z. Balevicius; V. Vaicikauskas; G.-J. Babonas (pp. 640-644).

Total internal reflection ellipsometry (TIRE) technique was used to investigate the role of surface roughness in the hybrid system composed of octadecanethiole layer on Au thin film. The samples with Au films of different microstructure were explored. The experimental results were interpreted in the model, which took into account the surface roughness of Au film in the hybrid system. It was shown that optical parameters of octadecanethiole were in correspondence for samples of different microstructure in the case of adequate models used for interpretation of TIRE data.

Keywords: Total internal reflection ellipsometry; Spectroscopic ellipsometry; Surface plasmons; Self-assembled monolayers; Octadecanethiole

The role of surface roughness in total internal reflection ellipsometry of hybrid systems by Z. Balevicius; V. Vaicikauskas; G.-J. Babonas (pp. 640-644).

Keywords: Total internal reflection ellipsometry; Spectroscopic ellipsometry; Surface plasmons; Self-assembled monolayers; Octadecanethiole

Self-affinity study of nanostructured porous silicon–crystalline silicon interfaces by J. Escorcia-Garcia; R. Cruz-Silva; V. Agarwal (pp. 645-649).

Self-affinity was used to analyze the roughness at the porous silicon (PS)–crystalline Si (cSi) interfaces fabricated under different conditions. Using the variable bandwidth method, the self-affinity behavior was, qualitatively and quantitatively, analyzed from the cross-section micrographs of the PS samples obtained by field emission scanning electron microscope. The results show that correlation length is related with the average pore width. Roughness exponent is found to be correlated with the interface roughness. In addition, similar experimental roughness exponents were obtained for several interfaces grown by different methods, indicating the intrinsic fractal nature of the PS–cSi interfaces. The results were confirmed through the self-affinity analysis done on the atomic force microscopy profiles.

Keywords: Porous silicon; Interfaces; Self-affinity; Fractals

Self-affinity study of nanostructured porous silicon–crystalline silicon interfaces by J. Escorcia-Garcia; R. Cruz-Silva; V. Agarwal (pp. 645-649).

Keywords: Porous silicon; Interfaces; Self-affinity; Fractals

Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation by Yunlong Wang; Zhaohua Jiang; Zhongping Yao (pp. 650-656).

Ceramic coatings were successfully prepared on steel by plasma electrolytic oxidation (PEO) in aluminate electrolyte and silicate electrolyte, respectively. The microstructure of the coatings including surface morphology, phase and element composition were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The bonding strength between the ceramic coating and the substrate was tested using different methods including tensile tests and shearing tests. The thermal shock resistance of the coatings was also evaluated. The results indicated that coatings obtained in both electrolytes were porous and coarse. The average diameters of the pores were below 10μm. PEO coatings obtained in aluminate electrolyte were composed of Fe₃O₄ and FeAl₂O₄, while those obtained in silicate electrolyte were in a noncrystal state. PEO coatings obtained in aluminate electrolyte showed similar change trend of tensile strength and shearing strength with increasing treating time, namely, a relatively high values with middle time treating and low value with short and long time treating. The best coating was the samples treated with 30min, whose tensile strength was 20.6MPa and shearing strength was 16MPa. The tensile strength and shearing strength of coatings obtained in silicate electrolyte were not strongly influenced by the treating time, the values of which were range in 14±2MPa and 11±2MPa, respectively. Coatings obtained in both electrolytes showed the best thermal shock resistance with middle time treating. Coatings obtained in silicate electrolyte show a little better thermal shock resistance than those obtained in aluminate electrolyte.

Keywords: Plasma electrolytic oxidation; Ceramic coating; Steel; Corrosion; Bonding strength; Thermal shock

Microstructure, bonding strength and thermal shock resistance of ceramic coatings on steels prepared by plasma electrolytic oxidation by Yunlong Wang; Zhaohua Jiang; Zhongping Yao (pp. 650-656).

Keywords: Plasma electrolytic oxidation; Ceramic coating; Steel; Corrosion; Bonding strength; Thermal shock

Effects of surface-modification with Bi₂O₃ on the thermal stability and photoinduced charge property of nanocrystalline anatase TiO₂ and its enhanced photocatalytic activity by Liqiang Jing; Jia Wang; Yichun Qu; Yunbo Luan (pp. 657-663).

Bi₂O₃ surface-modified TiO₂ nanoparticle has been synthesized by sol-hydrothermal processes, followed by post-treatment with an appropriate amount of bismuth nitrate solution, and also characterized by XRD, Raman, BET, TEM, FT-IR, XPS, UV–vis DRS and SPS techniques. The effects of the surface-modification with Bi₂O₃ on the thermal stability, photoinduced charge separation and photocatalytic activity for degrading rhodamine B (or phenol) under ultraviolet (or visible) irradiation are investigated in detail, along with their relationships and the activity enhancement mechanisms are also suggested. The results show that the modification with Bi₂O₃ can improve the thermal stability of the as-prepared anatase crystallites, consequently enhancing the anatase crystallinity so as to promote the photoinduced charge separation. And the modification with Bi₂O₃ also extends the optical response range. It can be concluded that the activity enhancement of surface-modified TiO₂ is mainly attributed to the increase in the photoinduced charge separation rate and to the extent of the optical response range, compared with un-modified ones. Moreover, the inhibition phase transformation mechanism related to Bi₂O₃ is suggested.

Keywords: TiO; ₂; Surface-modification with Bi; ₂; O; ₃; Anatase thermal stability; Charge separation; Photocatalysis

Superhydrophobic and luminescent methylsilicone resin film by Qihua Wang; Weixin Hou; Yaoming Zhang (pp. 664-667).

The europium complex, Eu(BA)₃Phen was introduced to the methylsilicone resin film, the investigation showed that the variation of the morphology and surface components of the film was not obvious comparing to methylsilicone resin film, and the superhydrophobicity of the as-prepared film was still retained. Furthermore, the film showed excellent luminescent property, the red light can be observed.

Keywords: Methylsilicone resin; Superhydrophobicity; Luminescent

Superhydrophobic and luminescent methylsilicone resin film by Qihua Wang; Weixin Hou; Yaoming Zhang (pp. 664-667).

Keywords: Methylsilicone resin; Superhydrophobicity; Luminescent

High-temperature oxidation behaviors of CVD diamond films by Jui-Chen Pu; Sea-Fue Wang; James C. Sung (pp. 668-673).

In this study, high-temperature oxidation of single-crystal diamond and diamond films prepared by hot filament chemical vapor deposition (HF-CVD), were characterized using thermal analysis and high-temperature in-situ Raman analysis. The measurements were performed in various temperatures up to 1300°C in air and N₂ atmospheres. The results indicate that the initial oxidization temperature of diamond film deposited at 700°C (D700 film) is ≈629°C, lower than those of diamond film deposited at 900°C (D900 film, ≈650°C) and single-crystalline diamond (≈674°C) in air. Oxidation rate of D700 film at high temperatures appeared to be the highest among the samples studied. A likely cause lies in the fact that, compared to their D900 sample, D700 diamond film contains a larger amount of non-diamond carbon and grain boundaries. However, D900 and D700 diamond films as well as single-crystalline diamond showed no detectable weight loss and oxidization when they were heated up to 1300°C in N₂ atmosphere.

Keywords: High-temperature oxidation; Diamond films; Thermal analysis; Raman analysis

High-temperature oxidation behaviors of CVD diamond films by Jui-Chen Pu; Sea-Fue Wang; James C. Sung (pp. 668-673).

Keywords: High-temperature oxidation; Diamond films; Thermal analysis; Raman analysis

Anomalous scaling in surface roughness evaluation of electrodeposited nanocrystalline Pt thin films by G. Nabiyouni; B. Jalali Farahani (pp. 674-682).

Atomic force microscopy (AFM) is used to measure the surface roughness of crystalline Pt thin films as a function of film thickness and growth rate. Our films were electrodeposited on Au/Cr/glass substrates, under galvanostatic control (constant current density), from a single electrolyte containing Pt⁴⁺ ions. Crystalline structure of the films was confirmed by X-ray diffraction (XRD) technique. The effect of growth rate (deposition current density) and film thickness (deposition time) on the kinetic roughening of the films were studied using AFM and roughness calculation. The data is consistent with a rather complex behaviour known as “anomalous scaling” where both local and large scale roughnesses show power law dependence on the film thickness.

Keywords: Atomic force microscopy (AFM); Surface roughness; Electrodeposition; Anomalous scaling

Anomalous scaling in surface roughness evaluation of electrodeposited nanocrystalline Pt thin films by G. Nabiyouni; B. Jalali Farahani (pp. 674-682).

Keywords: Atomic force microscopy (AFM); Surface roughness; Electrodeposition; Anomalous scaling

Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films by E. Krumov; N. Starbov; K. Starbova; A. Perea; J. Solis (pp. 683-687).

Excimer laser processing is applied for tailoring the surface morphology and phase composition of CeO₂ ceramic thin films. E-beam evaporation technique is used to deposit samples on stainless steel and silicate glass substrates. The films are then irradiated with ArF* excimer laser pulses under different exposure conditions. Scanning electron microscopy, optical spectrophotometry, X-ray diffractometry and EDS microanalysis are used to characterize the non-irradiated and laser-processed films. Upon UV laser exposure there is large increase of the surface roughness that is accompanied by photo-darkening and ceria reduction. It is shown that the laser induced changes in the CeO₂ films facilitate the deposition of metal nano-aggregates in a commercial copper electroless plating bath. The significance of laser modification as a novel approach for the production of CeO₂ based thin film catalysts is discussed.

Keywords: CeO; ₂; thin films; PVD; Excimer laser processing; Electroless plating

Laser assisted modification and chemical metallization of electron-beam deposited ceria thin films by E. Krumov; N. Starbov; K. Starbova; A. Perea; J. Solis (pp. 683-687).

Keywords: CeO; ₂; thin films; PVD; Excimer laser processing; Electroless plating

Ru/WCoCN as a seedless Cu barrier system for advanced Cu metallization by Dung-Ching Perng; Jia-Bin Yeh; Kuo-Chung Hsu (pp. 688-692).

The properties of Ru(5nm)/WCoCN(5nm) stacked layers as a seedless Cu barrier system has been investigated. Its barrier properties compared to single 10nm Ru film were investigated by sheet resistances, X-ray diffraction patterns, transmission electron microscopy, energy dispersive spectrometry spot analysis, line scans, and leakage currents. Thermal stability of the Ru(5nm)/WCoCN(5nm) improved by over 100°C than that of Ru(10nm) barrier. The results show that Ru(5nm)/WCoCN(5nm) can effectively block Cu diffusion up to 600°C for 30min. The Ru(5nm)/WCoCN(5nm) bilayer is a great Cu barrier candidate for seedless Cu interconnects.

Keywords: Copper interconnect; Copper diffusion barrier; Ru

Ru/WCoCN as a seedless Cu barrier system for advanced Cu metallization by Dung-Ching Perng; Jia-Bin Yeh; Kuo-Chung Hsu (pp. 688-692).

Keywords: Copper interconnect; Copper diffusion barrier; Ru

Preparation and characterization of the amorphous tungsten cone field emitter arrays by Ar⁺ etching by Fang Yan Xie; Li Gong; Xiao Liu; Jian Chen; Wei Guang Xie; Wei Hong Zhang; Shang Hui Chen (pp. 693-697).

Uniform amorphous tungsten cone arrays in high density were fabricated by Ar⁺ reduction etching of WO₃ nanowire film. The etching process was performed in the analysis chamber of an X-ray photoelectron spectroscopy (XPS) system. SEM and TEM results revealed that the tip radius of the etched cones was 10nm, and the cones were amorphous with a high aspect ratio of over 250. XPS analysis proved the cones to be metallic tungsten. In the aspect of field-emission property, the tungsten cone arrays had a lower turn-on field of 3MVm⁻¹ compared with 5MVm⁻¹ of the as-grown original WO₃ nanowire film.

Keywords: X-ray photoelectron spectrum; Ar ion etching; Amorphous tungsten; Tungsten oxide nanowire

X-ray photoelectron spectroscopy study of NiSi formation on shallow junctions by Yu-Long Jiang; Guo-Ping Ru; Xin-Ping Qu; Bing-Zong Li (pp. 698-701).

The influence of boron (B)/arsenic (As) on X-ray photoelectron spectroscopy (XPS) study of NiSi formation on shallow junctions is investigated in this paper. The Ni-silicide film was formed after 30s soak anneal at 450°C on ultra shallow p+/n or n+/p junctions. The atomic ratio of Ni/Si profile in depth was probed by XPS and the results show that a uniform NiSi layer forms on B-doped p+/n junction while a non-uniform, Ni-rich silicide layer forms on As-doped n+/p junction. It does not agree with the results of other independent phase identification methods such as X-ray diffraction, Rutherford backscattering spectroscopy, and Raman scattering spectroscopy, which all demonstrate the formation of NiSi on both n+/p and p+/n junctions. Comparing the raw binding energy spectra of Ni and Si for each silicide film, the similar spectra for Ni signals are revealed. But the Si signals with an obviously smaller intensity is found to be responsible for the apparent Ni rich silicide formation on As-doped n+/p junction. It indicates that As atoms in the silicide film can affect the sputtering yield of Ni and Si, while no noticeable effect is observed for B atoms. More As atoms than B atoms segregation into the silicide layer is indeed verified by secondary ion mass spectroscopy. And micro-Raman scattering spectroscopy further confirms that the degree of crystallinity for NiSi on n+/p junction is inferior to that on p+/n junction.

Keywords: PACS; 85.40.Ls; 82.80.Pv; 79.20.Rf; 68.35.DvNiSi; XPS; Dopant segregation; Preferred sputtering

X-ray photoelectron spectroscopy study of NiSi formation on shallow junctions by Yu-Long Jiang; Guo-Ping Ru; Xin-Ping Qu; Bing-Zong Li (pp. 698-701).

Keywords: PACS; 85.40.Ls; 82.80.Pv; 79.20.Rf; 68.35.DvNiSi; XPS; Dopant segregation; Preferred sputtering

Modification of magadiite surface by organofunctionalization for application in removing As(V) from aqueous media: Kinetic and thermodynamic by Denis L. Guerra; Alane A. Pinto; Rúbia R. Viana; Claudio Airoldi (pp. 702-709).

A synthetic Na-magadiite sample has been modified by organofunctionalization process using synthetic route involved the reaction of 2-mercaptopyrimidine with 3-chloropropyltriethoxysilane. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms adjusted to the Langmuir equation at room temperature and pH 2.0. The kinetic parameters analyzed by the Lagergren and Elovich models gave a good fit for a pseudo-second-order reaction with k₂ in the 4.9–14.0mmol⁻¹min⁻¹ range for M_MPY. The adsorption process was exothermic (Δ_int H=−4.09 to −5.79kJmol⁻¹) accompanied by increase in entropy (Δ_int S=41.29–61.80JK⁻¹mol⁻¹) and Gibbs energy (Δ_int G=−22.34 to −24.19kJmol⁻¹). The energetic effect caused by arsenic(V) cation adsorption was determined through calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.

Keywords: Adsorption; Na-magadiite; Kinetic; Thermodynamic properties; Arsenic

RETRACTED: Modification of magadiite surface by organofunctionalization for application in removing As(V) from aqueous media: Kinetic and thermodynamic by Denis L. Guerra; Alane A. Pinto; R bia R. Viana; Claudio Airoldi (pp. 702-709).

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the Editors of Applied Surface Science as fraudulent results have been found in this article and other publications in Elsevier journals by the same authors, namely, J. Colloid Interface Sci., 337 (2009) 122130, doi:10.1016/j.jcis.2009.05.013; Inorg. Chem. Commun., 12 (2009) 11451149, doi:10.1016/j.inoche.2009.08.029; J. Environ. Radioact., 101 (2010) 122133, doi:10.1016/j.jenvrad.2009.09.005; Process Saf. Environ. Prot., 88 (2010) 5361, doi:10.1016/j.psep.2009.10.002; J. Phys. Chem. Solids, 70 (2009) 14131421, doi:10.1016/j.jpcs.2009.08.012; Appl. Surf. Sci., 256 (2009) 702709, doi:10.1016/j.apsusc.2009.08.045; Inorg. Chem. Commun., 11 (2008) 2023, doi:10.1016/j.inoche.2007.09.029; Inorg. Chem. Commun, 12 (2009) 11071111, doi:10.1016/j.inoche.2009.08.033; J. Hazard. Mat., 172 (2009) 507514, doi:10.1016/j.jhazmat.2009.07.016; J. Hazard. Mat., 171 (2009) 514523, doi:10.1016/j.jhazmat.2009.06.032; J. Colloid Interface Sci., 338 (2009) 3039, doi:10.1016/j.jcis.2009.06.004.Publication of an article in a peer-reviewed journal is an important building-block in the development of science. Elsevier has defined policies and ethical guidelines that have to be obeyed by authors and editors and Elsevier takes its duties of guardianship over the scholarly record extremely seriously. The Editors of the Elsevier journals involved found that the allegations of fraud are conclusive and they have decided that these papers should be retracted from the journals.

Nanocrystalline nickel films with lotus leaf texture for superhydrophobic and low friction surfaces by Mehdi Shafiei; Ahmet T. Alpas (pp. 710-719).

Nanostructured Ni films with high hardness, high hydrophobicity and low coefficient of friction (COF) were fabricated. The surface texture of lotus leaf was replicated using a cellulose acetate film, on which a nanocrystalline (NC) Ni coating with a grain size of 30±4nm was electrodeposited to obtain a self-sustaining film with a hardness of 4.42GPa. The surface texture of the NC Ni obtained in this way featured a high density (4×10³mm⁻²) of conical protuberances with an average height of 10.0±2.0μm and a tip radius of 2.5±0.5μm. This structure increased the water repellency and reduced the COF, compared to smooth NC Ni surfaces. The application of a short-duration (120s) electrodeposition process that deposited “Ni crowns” with a larger radius of 6.0±0.5μm on the protuberances, followed by a perfluoropolyether (PFPE) solution treatment succeeded in producing a surface texture consisting of nanotextured protuberances that resulted in a very high water contact angle of 156°, comparable to that of the superhydrophobic lotus leaf. Additionally, the microscale protuberances eliminated the initial high COF peaks observed when smooth NC Ni films were tested, and the PFPE treatment resulted in a 60% reduction in the steady-state COFs.

Keywords: Nanocrystalline nickel; Surface nanotexturing; Lotus leaf; Superhydrophobicity; Friction

Nanocrystalline nickel films with lotus leaf texture for superhydrophobic and low friction surfaces by Mehdi Shafiei; Ahmet T. Alpas (pp. 710-719).

Keywords: Nanocrystalline nickel; Surface nanotexturing; Lotus leaf; Superhydrophobicity; Friction

Electronic structure of the organic semiconductor copper tetraphenylporphyrin (CuTPP) by Ian Reid; Yufeng Zhang; Alex Demasi; Andrew Blueser; Louis Piper; James E. Downes; Anne Matsuura; Greg Hughes; Kevin E. Smith (pp. 720-725).

The electronic structure of thin films of the organic semiconductor copper tetraphenylporphyrin (CuTPP) has been studied using synchrotron radiation-excited resonant soft X-ray emission spectroscopy (RSXE), near edge X-ray absorption fine structure (NEXAFS) spectroscopy, and X-ray photoemission spectroscopy (XPS). The C and N partial density of states for both the valence and conduction band electronic structure has been determined, while XPS was used to provide information on the chemical composition and the oxidation states of the copper. Good agreement was found between the experimental measurements of the valence and conduction bands and the results of density functional theory calculations.

Keywords: Copper tetraphenylporphyrin (CuTPP); X-ray photoemission spectroscopy; Resonant soft X-ray emission spectroscopy; X-ray absorption spectroscopy

Promoting effect of tin oxides on alumina-supported gold catalysts used in CO oxidation by Ferenc Somodi; Irina Borbáth; Mihály Hegedűs; Károly Lázár; István E. Sajó; Olga Geszti; Sergio Rojas; Jose Luis Garcia Fierro; József L. Margitfalvi (pp. 726-736).

In this study the influence of SnO_x nanoparticles on the catalytic performance of alumina-supported gold catalysts was investigated in CO oxidation. The tin modified supports were prepared by grafting of tetraethyltin onto the surface of alumina via its hydroxyl groups. The decomposition of organometallic surface species in oxygen yielded highly dispersed tin oxide on the surface of alumina. Gold was introduced onto the tin modified alumina support by both deposition–precipitation with urea and direct anionic exchange techniques using HAuCl₄ solution. Based on catalytic and different spectroscopic measurements it is suggested that the presence of “Sn n⁺-Au ensemble sites” is responsible for the increased activity of these catalysts.

Keywords: Au/alumina catalyst; Gold nano-sized; Tin oxide; CO oxidation; ¹¹⁹; Sn Mössbauer spectroscopy; XPS; FTIR spectroscopy

Reproducibility evaluation and Al doping of sol–gel-derived single- and multi-layer zinc oxide thin films by Mehmet Çopuroğlu; Shane O’Brien; Gabriel M. Crean (pp. 737-743).

Both single- and multi-layer thin films of sol–gel-derived undoped and Al-doped zinc oxide material systems were fabricated for potential use in transparent conducting oxide modules. Functional properties of the resultant films were characterised comparatively. High degree of reproducibility was demonstrated for the characterised properties, with the exception of the electrical conductivity. Influences of Al doping on the characterised properties were also investigated. Al doping reduced the average crystallite size, and led to a denser and less porous morphology, and also caused an increase in transparency in the UV region. Moreover, it was shown that the electrical conductivity of this thin film system could be improved upon either the application of a forming gas process, or Al doping.

Keywords: Zinc oxide; Functional properties; Reproducibility; Doping

Reproducibility evaluation and Al doping of sol–gel-derived single- and multi-layer zinc oxide thin films by Mehmet Çopuroğlu; Shane O’Brien; Gabriel M. Crean (pp. 737-743).

Keywords: Zinc oxide; Functional properties; Reproducibility; Doping

New tetramer structures in the initial process of Si homoepitaxial growth on Si (001) by Changqing Wang; Yongsheng Zhang; Yu Jia (pp. 744-748).

We have studied the interaction between Si ad-dimers in the initial process of Si homoepitaxial growth on Si (001) surface by molecular dynamics simulations using the Stillinger–Weber potential. The interactions determine the formation of larger clusters from diffusing dimers. We show different pathways for the formation of multiple-dimer clusters and propose two new tetramer structures (T_BB and T_CC) formation by two diffusing dimers interacting. These tetramer structures have been found to be energetically stable with respect to isolated ad-dimers. Moreover, their local bonding configuration is very similar to the B-type step edge which is known to be the favored adsorption site for epitaxial growth. The proposed tetramers may play a crucial role as the nucleus of the new epitaxial layer on Si (001).

Keywords: Stillinger–Weber potential; Molecular dynamics; Dimer; Si (0; 0; 1); Diffusion; Tetramer

New tetramer structures in the initial process of Si homoepitaxial growth on Si (001) by Changqing Wang; Yongsheng Zhang; Yu Jia (pp. 744-748).

Keywords: Stillinger–Weber potential; Molecular dynamics; Dimer; Si (0; 0; 1); Diffusion; Tetramer

Study on modes of energy action in laser-induction hybrid cladding by Yongjun Huang; Xiaoyan Zeng (pp. 749-756).

The shape and microstructure in laser-induction hybrid cladding were investigated, in which the cladding material was provided by means of three different methods including the powder feeding, cold pre-placed coating (CPPC) and thermal pre-placed coating (TPPC). Moreover, the modes of energy action in laser-induction hybrid cladding were also studied. The results indicate that the cladding material supplying method has an important influence on the shape and microstructure of coating. The influence is decided by the mode of energy action in laser-induction hybrid cladding. During the TPPC hybrid cladding of Ni-based alloy, the laser and induction heating are mainly performed on coating. During the CPPC hybrid cladding of Ni-based alloy, the laser and induction heating are mainly performed on coating and substrate surface, respectively. In powder feeding hybrid cladding, a part of laser is absorbed by the powder particles directly, while the other part of laser penetrating powder cloud radiates on the molten pool. Meanwhile, the induction heating is entirely performed on the substrate. In addition, the wetting property on the interface is improved and the metallurgical bond between the coating and substrate is much easier to form. Therefore, the powder feeding laser-induction hybrid cladding has the highest cladding efficiency and the best bond property among three hybrid cladding methods.

Keywords: Laser-induction hybrid cladding; Energy action; Mode; Microstructure

Study on modes of energy action in laser-induction hybrid cladding by Yongjun Huang; Xiaoyan Zeng (pp. 749-756).

Keywords: Laser-induction hybrid cladding; Energy action; Mode; Microstructure

The influence of boron content on electroanalytical detection of nitrate using BDD electrodes by J.T. Matsushima; W.M. Silva; A.F. Azevedo; M.R. Baldan; N.G. Ferreira (pp. 757-762).

Electrochemical response of nitrate reduction was analyzed using Boron Doped Diamond (BDD) films grown with different boron levels and it was correlated with the electrode physico-chemical properties. X-ray photoelectron spectroscopy and contact angle measurements showed the evolution of oxygen content and the weattability associated to the chemical surface modification as boron content increase in such films. Raman spectroscopy showed that the broad peaks at 1220 and 500cm⁻¹ become more evident with the boron addition. Electrochemical measurements by square wave voltammetry for nitrate reduction showed a strong dependence between the doping level of the BDD film and the nitrate detection. BDD film grown with B/C ratio of 20,000ppm presented the best sensibility to low concentration of nitrate. This result was analyzed from the linear relationship between the peak currents as a function of the nitrate concentration. This behavior was attributed to the changes in the diamond surface chemical and the film grain size.

Keywords: Diamond films; Electrodes; Detectors; Electrochemical

The influence of boron content on electroanalytical detection of nitrate using BDD electrodes by J.T. Matsushima; W.M. Silva; A.F. Azevedo; M.R. Baldan; N.G. Ferreira (pp. 757-762).

Keywords: Diamond films; Electrodes; Detectors; Electrochemical

The effect of annealing on the photoluminescent and optical properties of porous anodic alumina films formed in sulfamic acid by S. Stojadinovic; Z. Nedic; I. Belca; R. Vasilic; B. Kasalica; M. Petkovic; Lj. Zekovic (pp. 763-767).

Photoluminescent and optical properties of porous oxide films formed by two-step aluminum anodization at a constant potential of 30V in sulfamic acid have been investigated after their annealing, ranging from room temperature up to 600°C. X-ray diffraction reveals the amorphous nature of porous oxide films. Infrared and energy dispersive spectroscopy indicates the presence of sulfuric species incorporated in oxide films during the anodization. Photoluminescence (PL) measurements show PL bands in the range from 320 to 600nm. There are two peaks in emission and excitation spectra. One emission peak is at constant wavelength centered at 460nm and the other shifts from 390 to 475nm, depending on excitation wavelength. For excitation spectra, one spectral peak is at constant wavelength at 270nm and the other also shifts to longer wavelengths while increasing emission wavelength. Upon annealing of the as-prepared oxide films PL increases reaching maximum value at about 300°C and then decreases. The results indicate the existence of two PL centers, one placed at surface of the pore wall, while the other positioned inside the oxide films.

Keywords: Porous oxide films; Photoluminescence; Aluminum; Sulfamic acid; Annealing

Densely packed Ge quantum dots grown on SiO₂/Si substrate by L. Zhang; H. Ye; Y.R. Huangfu; C. Zhang; X. Liu (pp. 768-772).

We studied the growing process of Ge dots on silicon substrates covered with an ultrathin silicon dioxide buffer layer which was formed with simple chemical procedure. Uniform and densely packed (10¹¹cm⁻²) quantum dots (QDs) were obtained by optimizing the growth parameter with the MBE method. The influence of temperature, coverage, as well as the post-annealing process, on the epitaxial and non-epitaxial nanodots formation was evaluated. Nano-sized high density quantum dots were also realized with different growing conditions, whose structural and growing mechanism were discussed under the help of SEM and RHEED results.

Keywords: MBE; Ge quantum dots; RHEED; Silicon oxide; Non-epitaxial

Densely packed Ge quantum dots grown on SiO₂/Si substrate by L. Zhang; H. Ye; Y.R. Huangfu; C. Zhang; X. Liu (pp. 768-772).

Keywords: MBE; Ge quantum dots; RHEED; Silicon oxide; Non-epitaxial

Quantification of a Ti(C_xN1−_x) based multilayer by Auger Electron Spectroscopy by J. Guillot; T. Wirtz; T. Girot; M. Penoy; H.N. Migeon; G. Barbier (pp. 773-778).

Auger Electron Spectroscopy (AES) is an analytical technique sensitive to the surface of materials and providing elemental and chemical composition of conductive samples. The excellent spatial resolution and its quantification possibilities, even for light elements, make AES a commonly used technique to investigate surface and interfaces.TiN-like materials have a wide range of applications depending on their stoichiometry, but their composition is still complex (or at least not straightforward) to determine because of a strong overlapping of the Ti LMM with the N KLL Auger transitions. This quantification problem can be circumvented using computerised calculations as target factor analysis (TFA) to estimate the different nitrogen and titanium contributions in this peaks overlap. However, a more simple method, based on the study of Ti LMM and Ti LMV area ratio of pure TiN and TiC reference samples, is described in this paper and can be used to obtain the atomic composition of any titanium nitride based compound, whatever the complexity of the material. This method is an alternative to easily quantify TiN-like compounds by AES.As an illustration, a Ti(C_xN1−_x) based multilayer deposited on a hardmetal substrate was investigated. This quantification method was successfully used to evidence three different layers and the diffusion phenomenon at the interfaces between the layers. This study was completed with a quantitative SIMS depth profile that the high sensitivity and depth resolution allowed to measure the small variations of composition lower than the uncertainty of AES.

Keywords: AES; CMS; Quantification; TiCN; TFA

Quantification of a Ti(C_xN1−_x) based multilayer by Auger Electron Spectroscopy by J. Guillot; T. Wirtz; T. Girot; M. Penoy; H.N. Migeon; G. Barbier (pp. 773-778).

Keywords: AES; CMS; Quantification; TiCN; TFA

Optical reflectivity study of silicon ion implanted poly(methyl methacrylate) by Georgi B. Hadjichristov; Ivan L. Stefanov; Bojana I. Florian; Gergana D. Blaskova; Victor G. Ivanov; Eric Faulques (pp. 779-786).

The optical reflectivity (both specular and off-specular) of poly(methyl methacrylate) (PMMA) implanted with silicon ions (Si⁺) at energy of 50keV, is studied in the spectral range 0.25–25μm. The effect from the Si⁺ implantation on the reflectivity of two PMMA materials is examined in the dose range from 10¹⁴ to 10¹⁷ions/cm² and is linked to the structure formed in this ion implanted plastic. As compared to the pristine PMMA, an enhancement of the reflectivity of Si⁺ implanted PMMA is observed, that is attributed to the modification of the subsurface region of PMMA upon the ion implantation. The ion-produced subsurface organic interface is also probed by laser-induced thermo-lens.

Keywords: PACS; 42.70.Jk; 61.82.Pv; 78.40.Me; 78.68. +mIon implanted polymers; Optical properties; Diffuse reflectivity; Specular reflectivity; Poly(methyl methacrylate) (PMMA); Materials science

Synthesis and characterization of silver–polypyrrole film composite by Mohamad. M. Ayad; Eman Zaki (pp. 787-791).

In this work, we report the chemical polymerization of pyrrole to obtain thin film of polypyrrole (PPy) hydrochloride deposited onto the electrode of the quartz crystal microbalance (QCM). The film in the base form was exposed to a solution of AgNO₃. Electroless reduction for silver ions by the PPy film took place and silver particles were adsorbed onto the film surface. The silver particles content at the PPy films were analyzed by QCM and the results showed that the concentrations of silver uptakes increase as the original AgNO₃ solution increases. The morphology of the surface of the PPy film and the silver–PPy film composite were studied by the scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometry (EDX). They showed that the obtained silver particles have spherical, cubic and tetrahedral structures. X-ray diffraction (XRD) and Fourier transformed infra-red spectroscopy (FTIR) were used to characterize the structure of the powder composite. This work reveals the capability of PPy film coating on QCM in sensing and removing silver from several environmental samples.

Keywords: Quartz crystal microbalance; Sensor; Polypyrrole; Silver; Composite

Synthesis and characterization of silver–polypyrrole film composite by Mohamad. M. Ayad; Eman Zaki (pp. 787-791).

Keywords: Quartz crystal microbalance; Sensor; Polypyrrole; Silver; Composite

Relationship between the photoluminescence and conductivity of undoped ZnO thin films grown with various oxygen pressures by Chang-Feng Yu; Che-Wei Sung; Sy-Hann Chen; Shih-Jye Sun (pp. 792-796).

The pulsed laser deposition (PLD) technique is used to deposit undoped ZnO thin films on glass substrates at 150°C with different oxygen pressures of 40, 80, 100 and 150mTorr. X-ray diffraction (XRD) and atomic force microscopy (AFM) studies indicated that the obtained ZnO thin films were hexagonal wurtzite-type structures with strong (002) c-axis orientation. The relationship between photoluminescence and the conductivity of the ZnO thin films grown by pulsed laser deposition at various oxygen pressures was also discussed. The intensity of the deep-level-emission (DLE) and conductivity generally increased as the oxygen pressure decreased. The intensity of DLE peak was generally proportional to the conductivity. The band gap energy values, determined from transmittance spectra, were around 3.30–3.34eV, and decreased when the oxygen pressure increased.

Keywords: Pulsed laser deposition; Undoped ZnO; Deep-level-emission; Conductivity

Relationship between the photoluminescence and conductivity of undoped ZnO thin films grown with various oxygen pressures by Chang-Feng Yu; Che-Wei Sung; Sy-Hann Chen; Shih-Jye Sun (pp. 792-796).

Keywords: Pulsed laser deposition; Undoped ZnO; Deep-level-emission; Conductivity

Microstructure and corrosion resistance of the layers formed on the surface of precipitation hardenable plastic mold steel by plasma-nitriding by Dong Cherng Wen (pp. 797-804).

Plasma-nitriding is used to improve the wear resistance and corrosion resistance of plastic mold steels by modifying the surface layers of these steels. In this study, a precipitation hardenable plastic mold steel (NAK80) was plasma-nitrided at 470, 500, and 530°C for 4, 8, and 12h under 25% N₂+75% H₂ atmosphere in an industrial nitriding facility. The microstructures of the base material and nitrided layers as well as the core hardness were examined, and various phases present were determined by X-ray diffraction. The corrosion behaviors were evaluated using anodic polarization tests and salt fog spray tests in 3.5% NaCl solution.The results had shown that plasma-nitriding does not cause the core to soften by overaging. Nitriding and aging could be achieved simultaneously in the same treatment cycle. Plasma-nitriding of NAK80 mold steel produced a nitrided layer composed of an outer compound layer constituting a mixture of ɛ-nitride and γ′-nitride and an adjacent nitrogen diffusion layer on the steel surface. The amount of ɛ-nitride and total nitrides increased with an increase in nitriding temperature and nitriding time. Corrosion study revealed that plasma-nitriding significantly improved the corrosion resistance in terms of corrosion potential, corrosion and pitting current density, and corrosion rate. This improvement was found to be directly related to the increase in the amount of ɛ-nitride at the surface, indicating the amount of ɛ-nitride controlling the corrosion resistance.

Keywords: PACS; 81.65.Lp; 82.45.Bb; 61.05.cpPlasma nitriding; Plastic mold steel; Nitrides; Corrosion

Microstructure and corrosion resistance of the layers formed on the surface of precipitation hardenable plastic mold steel by plasma-nitriding by Dong Cherng Wen (pp. 797-804).

Keywords: PACS; 81.65.Lp; 82.45.Bb; 61.05.cpPlasma nitriding; Plastic mold steel; Nitrides; Corrosion

Self-assembled hemocompatible coating on poly (vinyl chloride) surface by Zhengbao Zha; Yan Ma; Xiuli Yue; Meng Liu; Zhifei Dai (pp. 805-814).

A stable hemocompatible coating was fabricated by consecutive alternating adsorption of iron (III) and two kinds of polysaccharides, heparin (Hep) and dextran sulfate (DS), onto poly (vinyl chloride) (PVC) surfaces via electrostatic interaction. The fluctuation of contact angles with the alternative deposition of iron (III) and polysaccharides verified the progressive buildup of the mulitilayer coating onto the PVC surface. Atomic force microscopy (AFM) analysis revealed that the PVC surfaces were completely masked by iron–polysaccharides multilayer coatings. The activated partial thromboplastin time (APTT) assay showed that both Hep/Fe³⁺/Hep and DS/Fe³⁺/Hep coated PVC were less thrombogenic than the uncoated one. Chromogenic assay for heparin activity proved definitively that the inhibition of locally produced thrombin was ascribed to the thromboresistance of the surface-bound heparin. Compared with the unmodified PVC surfaces, iron–polysaccharide multilayer coating presented a drastically reduced adhesion in vitro of platelets, polymorphonuclear neutrophil leukocytes (PMN) and peripheral blood mononuclear cells (PBMC). Interestingly, the DS/Fe³⁺/Hep coating was found to exhibit higher hydrophilicity and stability, hence lower non-specific protein adsorption in comparison with Hep/Fe³⁺/Hep coating due to the incorporation of dextran sulfate into the multilayer coating.

Keywords: Anticoagulant coating; Iron; Heparin; Hemocompatibility; Layer-by-layer self-assembly

Self-assembled hemocompatible coating on poly (vinyl chloride) surface by Zhengbao Zha; Yan Ma; Xiuli Yue; Meng Liu; Zhifei Dai (pp. 805-814).

Keywords: Anticoagulant coating; Iron; Heparin; Hemocompatibility; Layer-by-layer self-assembly

Tuning the geometry of shape-restricted DNA molecules on the functionalized Si(111) by Xiaochun Zhang; Ioanna H. Antonopoulos; Sandip Kumar; Junghuei Chen; Andrew V. Teplyakov (pp. 815-818).

Designing a well-defined and stable interface between biomolecules and semiconductor surfaces is of great importance for current and future biosensing and bioelectronic applications. The well-characterized chemistry, stability, and easily tunable electronic properties of silicon substrate make it a practical platform for this type of interface. It has been established in our previous work that a robust, covalent attachment between thiol-DNA molecules of a pre-designed geometrical shape and a modified silicon surface can be achieved. This work focuses on using this binding model and altering the distance between the DNA molecules and silicon surface by strategically placing thiol linkers within the pre-determined geometric design of the rectangularly shaped DNA. The statistical analysis of the height profiles of DNA molecules attached to the surface, as determined by AFM, provides specific insight into how the construction of the DNA molecules affects the binding distance. A comparison between two thiol-DNA molecules with different numbers of thiol groups placed either within the rectangular shape or anchored to the free loop of the same geometric design suggest that the average distance of these molecules to the functionalized silicon surface can be changed by approximately 0.5nm.

Keywords: Silicon substrate; DNA; Atomic force microscopy; Bio-field effect transistors (Bio-FETs)

Tuning the geometry of shape-restricted DNA molecules on the functionalized Si(111) by Xiaochun Zhang; Ioanna H. Antonopoulos; Sandip Kumar; Junghuei Chen; Andrew V. Teplyakov (pp. 815-818).

Keywords: Silicon substrate; DNA; Atomic force microscopy; Bio-field effect transistors (Bio-FETs)

Self-limiting growth of ZnO films on (0001) sapphire substrates by atomic layer deposition at low temperatures using diethyl-zinc and nitrous oxide by Yen-Ting Lin; Ping-Han Chung; Hung-Wei Lai; Hsin-Lun Su; Dong-Yuan Lyu; Kuo-Yi Yen; Tai-Yuan Lin; Chung-Yuan Kung; Jyh-Rong Gong (pp. 819-822).

Atomic layer deposition (ALD) of zinc oxide (ZnO) films on (0001) sapphire substrates was conducted at low temperatures by using diethyl-zinc (DEZn) and nitrous oxide (N₂O) as precursors. It was found that a monolayer-by-monolayer growth regime occurred at 300°C in a range of DEZn flow rates from 5.7 to 8.7μmol/min. Furthermore, the temperature self-limiting process window for the ALD-grown ZnO films was also observed ranging from 290 to 310°C. A deposition mechanism is proposed to explain how saturated growth of ZnO is achieved by using DEZn and N₂O. Transmission spectroscopic studies of the ZnO films prepared in the self-limiting regime show that the transmittances of ZnO films are as high as 80% in visible and near infrared spectra. Experimental results indicate that ZnO films with high optical quality can be achieved by ALD at low temperatures using DEZn and N₂O precursors.

Keywords: ZnO; Atomic layer deposition; Absorption spectroscopy

Study of the surface cleaning of GOI and SGOI substrates for Ge epitaxial growth by Yoshihiko Moriyama; Norio Hirashita; Koji Usuda; Shu Nakaharai; Naoharu Sugiyama; Eiji Toyoda; Shin-ichi Takagi (pp. 823-829).

An effective wet cleaning process, optimized for low temperature Ge epitaxial growth on thin Ge or SiGe structures with reduced surface roughening, is proposed. It is found that HF+HCl cleaning is the most effective wet cleaning method that is applicable to the low temperature thermal cleaning. It is also found that temperature of the thermal cleaning appropriate to 25–30nm thick germanium on insulator (GOI) or silicon–germanium on insulator (SGOI) substrates is approximately 450°C. Moreover, it is also found that the temperatures of Ge epitaxial growth even in lattice-matched systems must be reduced to around 400°C to prevent surface roughening and those in lattice-mismatched systems also must be reduced sufficiently (300°C for strained Ge growth on SGOI ( X_eff=0.6)) to prevent lattice relaxation as well as surface roughening. Finally, the successful formation of the compressively strained GOI structures is demonstrated by applying these wet cleaning and low temperature thermal cleaning processes and low temperature Ge epitaxy to thin SGOI substrates.

Keywords: Ge; GOI; SiGe; SGOI; Surface cleaning; Wet cleaning; Ge surface; Strained Ge; Epitaxy; Epitaxial growth

On the spray-drying deposition of TiO₂ photocatalytic films by M. Uzunova-Bujnova; R. Todorovska; M. Milanova; R. Kralchevska; D. Todorovsky (pp. 830-837).

The photocatalytic activity of TiO₂ films deposited on different substrates by the spray-drying method using suspensions of commercially available TiO₂ (Degussa P25 or Tronox) as starting material was studied. The influence of the type of the initial TiO₂, preparation conditions (temperature of the substrate during the film deposition, temperature of the post-deposition annealing), substrate material (glass, fused silica, stainless steel and graphite), the presence of additives in the spraying suspension (polyethylene glycol, ethylene glycol and acetylacetone) and its sonication before spraying on the morphology, size of crystallites and phase composition (rutile/anatase ratio) was studied. Optimal conditions for spray deposition of the films are suggested.

Keywords: PACS; 81.15.Rs; 81.20.Fw; 82.20.Pm; 82.50.Hp; 61.05.−aPhotocatalysis; TiO; ₂; Thin films; Spray-drying; X-ray diffractometry; SEM

On the spray-drying deposition of TiO₂ photocatalytic films by M. Uzunova-Bujnova; R. Todorovska; M. Milanova; R. Kralchevska; D. Todorovsky (pp. 830-837).

Keywords: PACS; 81.15.Rs; 81.20.Fw; 82.20.Pm; 82.50.Hp; 61.05.−aPhotocatalysis; TiO; ₂; Thin films; Spray-drying; X-ray diffractometry; SEM

The interface reaction of high-k La₂Hf₂O₇/Si thin film grown by pulsed laser deposition by Xuerui Cheng; Zeming Qi; Guobin Zhang; Yonghu Chen; Tingting Li; Guoqiang Pan; Min Yin (pp. 838-841).

The La₂Hf₂O₇ films have been deposited on Si (100) substrate by using pulsed laser deposition (PLD) method. X-ray diffraction (XRD) demonstrates that the as-grown film is amorphous and crystallizes after 1000°C annealing. The interface structure is systematically studied by Synchrotron X-ray reflectivity (XRR), Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS). Silicide, silicate and SiO_x formations from interfacial reaction are observed on the surface of the Si substrate in the as-grown film. The impact of silicide formation on the electrical properties is revealed by capacitance–voltage ( C– V) measurements. By post-deposition annealing (PDA), silicide can be effectively eliminated and C– V property is obviously improved.

Keywords: Thin films; Laser deposition; Interface

Weathering of copper–amine treated wood by Jun Zhang; D. Pascal Kamdem; Ali Temiz (pp. 842-846).

In this study, the effect of ultraviolet light (UV) irradiation and water spray on color, contact angle and surface chemistry of treated wood was studied. Southern pine sapwood ( Pinus Elliottii.Engelm.) treated with copper ethanolamine (Cu-MEA) was subjected to artificially accelerated weathering with a QUV Weathering Tester. The compositional changes and the surface properties of the weathered samples were characterized by Fourier transform infrared (FTIR) spectroscopy, color and contact angle measurements. FTIR indicated that MEA treatment was not found to slow down wood weathering. FTIR spectrum of MEA-treated sample was similar to that of the untreated SP. However, the Cu-MEA treatment retarded the surface lignin degradation during weathering. The main changes in FTIR spectrum of Cu-MEA treatment took place at 915, 1510, and 1595cm⁻¹. The intensity of the bands at 1510 and 1595cm⁻¹ increased with the Cu-MEA treatment. Both untreated and MEA-treated exhibited higher Δ E than the Cu-MEA treated samples, indicating that MEA treatment did not retard color changes. However, Δ E decreased with increasing copper concentration, suggesting a positive contribution of Cu-EA to wood color stability. The contact angle of untreated and MEA-treated samples changed rapidly, and dropped from 75±5° to 0° after artificial weathering up to 600h. Treatment with Cu-MEA slowed down the decreasing in contact angle. As the copper concentration increases, the rate of change in contact angle decreases.

Keywords: Weathering; CIELAB; FTIR; QUV; Contact angle; Copper amine

Weathering of copper–amine treated wood by Jun Zhang; D. Pascal Kamdem; Ali Temiz (pp. 842-846).

Keywords: Weathering; CIELAB; FTIR; QUV; Contact angle; Copper amine

Atomic layer deposition of ytterbium oxide usingβ-diketonate and ozone precursors by M. Bosund; K. Mizohata; T. Hakkarainen; M. Putkonen; M. Söderlund; S. Honkanen; H. Lipsanen (pp. 847-851).

Yb₂O₃ thin films were grown onto Si(100) and glass substrates by atomic layer deposition using Yb(thd)₃ and ozone precursors. Self saturating growth appeared when the growth temperature was between 300 and 350°C. Polycrystalline BCC structure with (222), (400), (411), (440), (611) and (622) orientations was observed using X-ray diffraction measurements with lattice constanta0=10.4Å. The mass density for the films grown at 300 and 350° C was found to be 8.9 and 9.0g/cm³, respectively. The film roughness increased with growth temperature from 0.9 (at 300°C) to 1.3nm (350°C). Elastic recoil detection analysis revealed that the Yb/O ratio of the films grown at 350° C was 0.63 and the films contained 1.1% hydrogen, 0.7% carbon and 0.08% nitrogen impurities. The refractive index of the film was about 1.9 at near-IR wavelength.

Keywords: PACS; 81.15.; −; z; 71.20.Eh; 78.70.Ck; 78.66.Bz; 68.55.Ln; 68.37.PsAtomic layer deposition; Ytterbium oxide; TOF-ERDA; X-ray diffraction; X-ray reflectivity; Refractive index

Atomic layer deposition of ytterbium oxide usingβ-diketonate and ozone precursors by M. Bosund; K. Mizohata; T. Hakkarainen; M. Putkonen; M. Söderlund; S. Honkanen; H. Lipsanen (pp. 847-851).

Keywords: PACS; 81.15.; −; z; 71.20.Eh; 78.70.Ck; 78.66.Bz; 68.55.Ln; 68.37.PsAtomic layer deposition; Ytterbium oxide; TOF-ERDA; X-ray diffraction; X-ray reflectivity; Refractive index

Nanoparticulate cerium dioxide and cerium dioxide–titanium dioxide composite thin films on glass by aerosol assisted chemical vapour deposition by Uzma Qureshi; Charles W. Dunnill; Ivan P. Parkin (pp. 852-856).

Two series of composite thin films were deposited on glass by aerosol assisted chemical vapour deposition (AACVD)—nanoparticulate cerium dioxide and nanoparticulate cerium dioxide embedded in a titanium dioxide matrix. The films were analysed by a range of techniques including UV–visible absorption spectroscopy, X-ray diffraction, scanning electron microscopy and energy dispersive analysis by X-rays. The AACVD prepared films showed the functional properties of photocatalysis and super-hydrophilicity. The CeO₂ nanoparticle thin films displaying photocatalysis and photo-induced hydrophilicity almost comparable to that of anatase titania.

Keywords: Cerium dioxide; Chemical vapour deposition; Photocatalyst; Hydrophilic

Laser-induced surface modification of polystyrene by Piotr Rytlewski; Marian Żenkiewicz (pp. 857-861).

The modification induced in polystyrene (PS) by the ArF excimer laser radiation has been investigated. Various numbers of the laser pulses of the energies below the material ablation threshold were applied. Changes in the chemical composition of the PS surface layer were studied by the X-ray photoelectron spectroscopy (XPS). Analysis of the morphological changes in the polymer surface layer was performed via the atomic force microscopy (AFM). The contact angles of test liquids (water and diiodomethane) were measured with use of a goniometer while the surface energy (SE) was calculated by the Owens–Wendt method. It was found that the surface energy change was mainly affected by surface roughness caused by the laser radiation and that surface oxidation had not considerably contributed to this change. The increase in the SE was mostly due to its disperse component.

Keywords: Laser modification; Polystyrene; Oxidation; Wettability; Surface energy

Laser-induced surface modification of polystyrene by Piotr Rytlewski; Marian Żenkiewicz (pp. 857-861).

Keywords: Laser modification; Polystyrene; Oxidation; Wettability; Surface energy

Evaluation for the configurational and electronic state of SO₃ adsorbed on Pt surface by Chikashi Suzuki; Yoichi Yamada; Toshio Nakagiri (pp. 862-869).

We evaluate the adsorption of SO₃ molecule on the Pt (111) surface using the first-principles calculations by a slab model with a periodic boundary condition. We find that there are four stable adsorption configurations on the Pt surface, where SO₃ molecules are adsorbed above the three-fold fcc and hcp sites. In two of these configurations, S and two O atoms are bound to the Pt atoms, and in two other of them, all the three O atoms are bound to Pt surface atoms. Besides, it is found that molecular orbitals of SO₃ and those of Pt surface are hybridized in the active metal d-bands region, that the localized molecular orbitals in SO₃ are stabilized, and that the charge is transferred from Pt to S 3p by SO₃ adsorption on Pt surface though the other interaction of S and O (bound to Pt) component with Pt is little. In addition, the bond between S and O bound to Pt become weak by SO₃ adsorption on Pt surface because the charge polarization to O–Pt bond weakens the bond between S and O bound to Pt. This interaction is assumed to encourage the breakage of S–O bond.

Keywords: Sulfur trioxide; Pt surface; First-principles calculation; Hybrid thermo-chemical process; Structural optimization; Electronic structure; Chemical bonding state; Charge density

Evaluation for the configurational and electronic state of SO₃ adsorbed on Pt surface by Chikashi Suzuki; Yoichi Yamada; Toshio Nakagiri (pp. 862-869).

Keywords: Sulfur trioxide; Pt surface; First-principles calculation; Hybrid thermo-chemical process; Structural optimization; Electronic structure; Chemical bonding state; Charge density

Biaxial stresses, surface roughness and microstructure in evaporated TiO₂ films with different deposition geometries by Chuen-Lin Tien (pp. 870-875).

The residual stresses, surface roughness and microstructure in titanium oxide films prepared by electron-beam evaporation and deposited with different geometries were investigated, with particular focus on the in-plane anisotropy of the biaxial stresses and microstructures. Thin films were deposited with various deposition angles on B270 glass substrates and silicon wafers. Two different types of deposition geometries were studied. The residual stress in the thin films was examined by a phase-shifting Twyman-Green interferometer. The optical constants, biaxial stress and surface roughness were found to be related to the evolution of the anisotropic microstructures in the films. The results revealed that the anisotropic stresses that developed in the evaporated titanium oxide films were dependent upon the deposition geometry and microstructure of the films.

Keywords: Thin film; Electron-beam evaporation; Biaxial stress

Biaxial stresses, surface roughness and microstructure in evaporated TiO₂ films with different deposition geometries by Chuen-Lin Tien (pp. 870-875).

Keywords: Thin film; Electron-beam evaporation; Biaxial stress

Effects of reactive gas on shear and fracture behaviors of plasma-treated polyethylene/steel joints by Ji Hoon Lee; Kyong Yop Rhee; Joong Hee Lee (pp. 876-883).

For this study, we investigated the effects of reactive gases (oxygen, nitrogen, and argon) on the shear behavior and fracture toughness of HDPE/steel joints by treating high-density polyethylene (HDPE) with plasma using a microwave method. We also investigated the effect of plasma treatment on the physical and chemical changes on the surface of HDPE. HDPE/steel joints were fabricated using a secondary bonding process. The results showed that the shear strength and fracture toughness of HDPE/steel joints treated with different reactive gases were ordered as follows, oxygen>nitrogen>argon. Specifically, the shear strength and fracture toughness of oxygen plasma-treated HDPE/steel joints were approximately 7600% and 2400% greater, respectively, than that of untreated HDPE/steel joints. The improvements in shear strength and fracture toughness are attributed to increase in surface roughness and the creation of carbonyl functional groups on the HDPE surface via plasma treatment.

Keywords: High-density polyethylene; Plasma treatment; Shear strength; Fracture toughness

Effects of reactive gas on shear and fracture behaviors of plasma-treated polyethylene/steel joints by Ji Hoon Lee; Kyong Yop Rhee; Joong Hee Lee (pp. 876-883).

Keywords: High-density polyethylene; Plasma treatment; Shear strength; Fracture toughness

A novel Ce, C-codoped TiO₂ nanoparticles and its photocatalytic activity under visible light by Jingjing Xu; Yanhui Ao; Degang Fu (pp. 884-888).

A novel photocatalyst (Ce, C-codoped titania) was synthesized through a modified sol–gel method under mild condition. The as-prepared sample was investigated by XRD, SEM, DRS and XPS. It was found that the as-prepared photocatalyst was composed of spheroidal particles, which were smaller than undoped ones. The absorbance spectrum of Ce, C-codoped TiO₂ exhibited significant red-shift to visible region. It can be ascribed to appearance of a new electronic state in the middle of the TiO₂ band-gap. Furthermore, cerium doping could slow the radiative recombination process of photogenerated electrons and holes in TiO₂. Accordingly, for degradation of dye Reactive Brillint Red X-3B (C.I. reactive red 2) under visible light, the photocatalytic activity of Ce, C-codoped TiO₂ improved much compared to other samples (C-doped TiO₂, undoped TiO₂ and P25).

Keywords: Ce; C-codoped; Titania; Photocatalysis; Visible light response; Low temperature

A novel Ce, C-codoped TiO₂ nanoparticles and its photocatalytic activity under visible light by Jingjing Xu; Yanhui Ao; Degang Fu (pp. 884-888).

Keywords: Ce; C-codoped; Titania; Photocatalysis; Visible light response; Low temperature

A novel one-step electron beam irradiation method for synthesis of Ag/Cu₂O nanocomposites by Xiangfeng Lin; Ruimin Zhou; Jianqiang Zhang; Shunting Fei (pp. 889-893).

In this paper, a novel method for fabrication of silver/cuprous oxide (Ag/Cu₂O) nanocomposites is reported. The method involves the reduction of Ag⁺ and Cu²⁺ in the aqueous solution to Ag/Cu₂O without adding any reducing reagent under electron beam (EB) irradiation. Dye methyl orange is used as the pollutant model to investigate the photocatalytic properties of these nanocomposites. The results reveal that they have higher photocatalytic efficiencies than that of Cu₂O under visible light. These visible light-sensitive catalysts may have potential application in the field of environmental remediation.

Keywords: Electron beam irradiation; Ag/Cu; ₂; O; Nanocomposites; Photocatalytic efficiencies

A novel one-step electron beam irradiation method for synthesis of Ag/Cu₂O nanocomposites by Xiangfeng Lin; Ruimin Zhou; Jianqiang Zhang; Shunting Fei (pp. 889-893).

Keywords: Electron beam irradiation; Ag/Cu; ₂; O; Nanocomposites; Photocatalytic efficiencies

Microtribological and electrochemical corrosion behaviors of polydopamine coating on APTS-SAM modified Si substrate by Junfei Ou; Jinqing Wang; Sheng Liu; Jinfang Zhou; Sili Ren; Shengrong Yang (pp. 894-899).

A polydopamine coating (coded as PDAc) was prepared successfully on a Si substrate through a two-step process. Briefly, to improve the adhesion of PDAc on the Si substrate, a self-assembled monolayer of 3-aminopropyl triethoxysilane (coded as APTS-SAM) was firstly generated on the bare Si wafer. Thereafter, the PDAc with different thickness was fabricated through the chemical adsorption and autopolymerization of the dopamine hydrochloride on the APTS-SAM coated Si substrate. The formation of PDAc on the APTS-SAM modified Si substrate was proved by the characterizations of contact angle measurement, attenuated total reflectance Fourier transform infrared (ATR-FTIR) analysis, and X-ray photoelectron spectroscope (XPS), etc. The ellipsometric thickness measurement and atomic force microscopy (AFM) image analysis showed that the PDAc became thicker and rougher with the deposition time prolongation. Microtribological study showed that the thickness and roughness of the PDAc played a significant role in the tribological properties. In comparison with the bare Si substrate, the PDAc with thinner thickness possessed lower friction and was anticipated to be used as protecting coating in the field of boundary lubrication. The electrochemical corrosion behaviors of the prepared PDAc were investigated using the electrochemical station and a low corrosion current density was revealed, implying that the PDAc had good anti-corrosion capability and might find potential applications in the field of corrosion resistance.

Keywords: Polydopamine coating; Polymerization; Friction; Electrochemical corrosion; Atomic force microscopy

Utilization of light scattering in transmission laser welding of medical devices by Jon Fold von Bülow; Kim Bager; Carsten Thirstrup (pp. 900-908).

This paper reports on optimization of material parameters in transmission laser welding of polymers including light absorption, light scattering and the thermal properties of the polymers. A criterion for making an optimized transmission laser weld between a transparent polymer part and an absorbing and scattering polymer part is formulated as a required thickness of the melt-zone in the transparent part with a corresponding minimum-line-energy-for-welding ( MLEW). Experimental data of MLEW are presented for a medical device application involving joining polyethylene-octene parts for various concentrations of near-infrared absorber and titanium dioxide light scattering particles. Numerical and analytical models yield good agreement to the experimental data and enable optimization of the transmission laser welding process. By utilization of light scattering, the laser line-energy required for joining two polymer parts can be reduced by a factor up to three, enabling a corresponding reduction of the cycle time in the manufacturing process.

Keywords: Polymer; Laser welding; Interface; Joining; Light scattering

Utilization of light scattering in transmission laser welding of medical devices by Jon Fold von Bülow; Kim Bager; Carsten Thirstrup (pp. 900-908).

Keywords: Polymer; Laser welding; Interface; Joining; Light scattering

Buckle morphologies of wedge-shaped Fe films quenched by silicone oil during deposition by Sen-Jiang Yu; Yong-Ju Zhang; Hong Zhou; Ping-Gen Cai; Miao-Gen Chen (pp. 909-915).

A characteristic wedge-shaped iron (Fe) film system, deposited on glass substrates by a DC-magnetron sputtering method and quenched by silicone oil during deposition, has been successfully fabricated. Telephone cord buckles induced by residual compressive stress can be widely observed in the samples. They are shown to nucleate and grow slowly in the atmosphere, but propagate rapidly after disturbance of the film by an external force. Various buckling phenomena, such as generation of disordered telephone cord networks on a isotropic substrate, formation of parallel wavy buckle and circular blister lines on a patterned substrate, partial healing of buckling by pushing the film back to the substrate during the propagation process, occurrence of straight-sided blisters near a step edge, are present in this paper.

Keywords: Wedge-shaped film; Compressive stress; Buckling; Sputtering; Quenching

Buckle morphologies of wedge-shaped Fe films quenched by silicone oil during deposition by Sen-Jiang Yu; Yong-Ju Zhang; Hong Zhou; Ping-Gen Cai; Miao-Gen Chen (pp. 909-915).

Keywords: Wedge-shaped film; Compressive stress; Buckling; Sputtering; Quenching

Fabrication of silver-coated silicon nanowire arrays for surface-enhanced Raman scattering by galvanic displacement processes by Xianzhong Sun; Linhan Lin; Zhengcao Li; Zhengjun Zhang; Jiayou Feng (pp. 916-920).

Silver-coated silicon nanowire (SiNW) arrays were prepared utilizing galvanic displacement processes consisting of three steps: galvanic displacement deposition of silver particles using a HF–AgNO₃ or NH₄F–AgNO₃ aqueous solution; formation of SiNW arrays by a silver-assisted chemical etching process conducted in the HF–H₂O₂ aqueous solution; deposition of silver particles on the SiNW arrays from the NH₄F–AgNO₃ aqueous solution. The effects of the morphology of pre-deposited silver particles and deposition solution on the formation of silver-coated SiNW arrays were discussed. Surface-enhanced Raman scattering (SERS) performances have been studied using Rhodamine 6G (R6G) probe molecules on the silver-coated SiNW substrates.

Keywords: PACS; 62.23.Hj; 62.23.Pq; 68.37.Hk; 81.65.Cf; 82.45.Jn; 82.45.VpSilicon nanowire arrays; Galvanic displacement; Silver-assisted chemical etching; Nanocomposites

Characterization of gadolinium oxide film by pulse laser deposition by Xinhong Cheng; Dapeng Xu; Zhaorui Song; Dawei He; Yuehui Yu; Qingtai Zhao; DaShen Shen (pp. 921-923).

In this work, Gd-oxide dielectric films were deposited on Si by pulse laser deposition method (PLD), moreover, the micro-structures and electrical properties were reported. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) indicated that Gd-oxide was polycrystalline Gd₂O₃ structure, and no Gd metal phase was detected. In addition, both interface at Si and Ni fully silicide (FUSI) gate were smooth without the formation of Si-oxide. X-ray photoelectron spectroscopy (XPS) confirmed the formation of Gd₂O₃ and gave an atom ratio of 1:1 for Gd:O, indicating O vacancies existed in Gd₂O₃ polycrystal matrix even at O₂ partial pressure of 20mTorr. Electrical measurements indicated that the dielectric constant of Gd-oxide film was 6 and the leakage current was 0.1A/cm² at gate bias of 1V.

Keywords: PACS; 77.55.+f; 73.40.QvHigh-; k; gate dielectrics; Gd-oxide; PLD

Characterization of gadolinium oxide film by pulse laser deposition by Xinhong Cheng; Dapeng Xu; Zhaorui Song; Dawei He; Yuehui Yu; Qingtai Zhao; DaShen Shen (pp. 921-923).

Keywords: PACS; 77.55.+f; 73.40.QvHigh-; k; gate dielectrics; Gd-oxide; PLD

Nanostructured sapphire vicinal surfaces as templates for the growth of self-organized oxide nanostructures by E. Thune; A. Boulle; D. Babonneau; F. Pailloux; W. Hamd; R. Guinebretière (pp. 924-928).

Vicinal substrates of sapphire with miscut angle of 10° from the (001) planes towards the [110] direction have been annealed in air in the range from 1000 to 1500°C. The behaviour of these surfaces has been characterized as a function of the temperature and the thermal treatment time by Atomic Force Microscopy observations. A thermal treatment at 1250°C allows to stabilize a surface made of periodically spaced nanosized step-bunches. Such stepped surfaces were used as template to grow self-patterned epitaxial oxide nanoparticles by thermal annealing of yttria-stabilized zirconia thin films produced by sol–gel dip-coating. Grazing Incidence Small Angle X-ray Scattering and High-Resolution Transmission Electron Microscopy were used to study the morphology of the nanoparticles and their epitaxial relationships with the substrate.

Keywords: Sapphire vicinal surfaces; Self-organized oxide nanostructure; AFM; GISAXS; HRTEM

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Applied Surface Science (v.256, #3)