Structure and Mechanical Performance of Nitrogen Doped Diamond-like Carbon Films

Nitrogen doped diamond-like carbon （DLC：N） films were prepared by electron cyclotron resonance chemical vapor deposition （ECR-CVD） on polycrystalline Si chips. Film thickness is about 50 nm. Auger electron spectroscopy （AES） was used to evaluate nitrogen content, and increasing N2 flow improved N content from 0 to 7.6%. Raman and X-ray photoelectron spectroscopy （XPS） analysis results reveal CN-sp^3C and N-sp^2C structure. With increasing the N2 flow, sp^3C decreases from 73.74% down to 42.66%, and so does N-sp^3C from 68.04% down to 20.23%. The hardness decreases from 29.18 GPa down to 19.74 GPa, and the Young＇s modulus from 193.03 GPa down to 144.52 GPa.     

Fullerene C60 coated silicon nanowires as anode materials for lithium secondary batteries

A Fullerene C60 film was introduced as a coating layer for silicon nanowires (Si NWs) by a plasma assisted thermal evaporation technique. The morphology and structural characteristics of the materials were studied by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). SEM observations showed that the shape of the nanowire structure was maintained after the C60 coating and the XPS analysis confirmed the presence of the carbon coating layer. The electrochemical characteristics of C60 coated Si NWs as anode materials were examined by charge-discharge tests and electrochemical impedance measurements. With the C60 film coating, Si NW electrodes exhibited a higher initial coulombic efficiency of 77% and a higher specific capacity of 2020 mA h g(-1) after the 30th cycle at a current density of 100 microA cm(-2) with cut-off voltage between 0-1.5 V. These improved electrochemical characteristics are attributed to the presence of the C60 coating layer which suppresses side reaction with the electrolyte and maintains the structural integrity of the Si NW electrodes during cycle tests.     

电化学沉积DLC膜及其表征

采用电化学沉积方法，甲醇有机溶剂作碳源，在直流电源作用下在单晶硅表面沉积得到碳薄膜。薄膜不溶于苯、丙酮等有机溶剂，具有较高的硬度(16GPa左右)，用AFM、Raman和FTIR分析手段对该薄膜表面形貌和结构进行表征，Raman和FTIR结果表明电化学沉积得到的是含氢的类金刚石碳薄膜。通过研究样品薄膜的XPS和XAES谱图特征，进一步证实薄膜是DLC薄膜，并用线性插入法估算出样品薄膜中SP^3的相对含量为60％，同时推测了电化学沉积DLC薄膜的生长机理。     

Preparation of diamond-like carbon films by cathodic micro-arc discharge in aqueous solutions

Diamond-like carbon films (DLC) and silicon doped diamond-like carbon films were deposited on Ni substrate by cathodic micro-arc discharge at room temperature in aqueous solutions. The deposit potential was 130 V. The structure of the films was characterized by a scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Raman spectra and XPS analysis demonstrated that the films were diamond-like carbon clearly. SEM observation showed that the DLC films were uniform and the thickness was about 200 nm. Potentiodynamic polarization curve indicated the corrosion resistance of the Ni substrate was markedly improved by DLC films.     

The effect of exposure to biological fluids on the spallation resistance of diamond-like carbon coatings on metallic substrates

Diamond-like carbon (DLC) films have been deposited by RF plasma-assisted glow discharge CVD on AISI 304 stainless steel and Ti–6Al–4V substrates. A substrate plastic straining technique (to measure the strength and adhesion of the coating) and erosion testing (to measure its durability) have been used, before and after exposure to various fluids (distilled water, phosphate buffered saline solution (PBS) and bovine serum). The films on both substrates had excellent adhesion before exposure to the fluid, being slightly higher for those on Ti substrates. PBS solution affected the adhesion adversely, whereas distilled water and serum had no apparent effect. Fourier transform infrared (FTIR) and Raman spectroscopic studies revealed that there were no changes in the atomic structure of the coatings during exposure. X-ray photoelectron spectroscopy (XPS) measurements indicated that PBS tends to penetrate through perforations in the film and attack the thin transition layer of graded Si/C composition between the a: Si–H layer and the DLC coating. An increase in exposure temperature increased the population of defects in samples exposed to PBS. Coatings on Ti exhibited similar characteristics, but were considerably more resistant to damage. This may be due to a lower incidence of defects and perforations in these films.     

Hydroxyapatite/Bioactive Glass Films Produced by a Sol–Gel Method: In Vitro Behavior

Hydroxyapatite (HA) and HA/bioactive glass (49S) films were deposited on Si(100) substrates by a sol–gel dip‐coating method. The microstructure and in vitro bioactivity of the films were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X‐ray photoelectron spectroscopy (XPS). Polycrystalline HA and amorphous bioactive glass films were obtained after annealing at 600 and 400 °C, respectively. The crystallization temperature of HA was determined to be around 568 °C. The surfaces of the HA films were covered with an apatite layer consists of spherulites formed by nanosized needle‐like aggregates after the soaking in simulated body fluid (SBF) for 10 days, while amorphous HA/bioactive glass surface was covered with larger spherical crystallites. Both XPS and EDS results obtained from HA/bioactive glass film, after soaking in SBF, showed increasing P amounts on the surface at the expense of Si. The higher density of the newly formed layer on HA/bioactive glass surface than that of the HA surface after 10 days of soaking was evidence of increased reaction rate and apatite forming ability when bioactive glass layer is present on the HA films.     

a-C:N膜的制备及结构分析

采用射频溅射法在锗衬底上沉积无定形碳氮膜 (a- C:N) ,用 X射线光电子谱 (XPS)、傅立叶变换红外光谱 (FT- IR)和喇曼光谱 (RS)分析了膜的成分与结构。结果表明 ,氮是以化学键的形式存在于膜中 ,且有三种不同的 C- N键合状态。随着反应气体中氮气分压的增加 ,a- C:N膜中氮浓度增加 ,C≡N键的含量增加。     

溅射靶功率对氮化碳薄膜结构的影响

利用双放电腔微波ECR等离子体增强非平衡磁控溅射技术,在Si(100)上制备氮化碳薄膜,并对薄膜进行了拉曼(Raman)、原子力显微镜(AFM)、X射线光电子谱(XPS)等结构的表征.发现溅射靶功率对制膜工艺、薄膜的结构和表面形貌产生很大影响.随着溅射靶功率的增大,薄膜的沉积速率减小,表面粗糙度增大,薄膜结构中的sp2含量增加.     

9Cr18轴承钢表面不同等离子体浸没离子注入强化处理技术研究

采用不同的等离子体浸没离子注入(PⅢ)工艺在9Cr18轴承钢表面进行了气体、金属、金属加气体的离子注入和碳化钛(TiC)、类金刚石(DLC)薄膜的等离子体浸没离子注入与沉积(PⅢD).对处理后的试样进行了X射线光电子能谱(XPS)、X射线衍射(XRD)、俄歇电子能谱(AES)和拉曼光谱(Raman)分析;测试了处理前后试样的显微硬度、磨痕宽度和摩擦系数.结果表明:处理后试样表面均形成了不同的改性层,且改性层中化学组成和各元素的浓度-深度分布随处理工艺的不同而变化;处理后试样的显微硬度都有较大提高,最大增幅达77.7%;表面摩擦系数由0.8下降到0.16;磨痕宽度减少了23倍;与PⅢ工艺相比,相同参数下,PⅢD处理后的试样表面综合性能更加优异.     

TiC coatings deposited onto carbon and molybdenum surfaces by electron beam evaporation

TiC coatings were deposited onto graphite and molybdenum substrates by an electron beam evaporation method. A titanium film 1000–10000 Å thick was evaporated onto the graphite substrate which was then heated at 1000 °C for 5 min to form the TiC film by an interdiffusion process. In the case of the molybdenum substrate, a double-layer film consisting of titanium and carbon (Ti/C/Mo) was prepared by evaporation and the subsequent heat treatment was performed at 700 °C or at 1000 °C for 5 min. The properties of the coatings were examined by various surface analysis techniques including Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Rutherford backscattering (RBS). The atomic ratio of carbon to titanium in these coatings was found to be 0.9. The in-depth profiles obtained by XPS examination showed that the coating prepared at 700 °C had a carbon layer between the TiC layer and the molybdenum substrate, while that prepared at 1000 °C had an Mo₂C layer between the coating and the substrate.     

Effects of thermal annealing on the structural and optical properties of carbon-implanted SiO2

Amorphous carbon (a-C) nanoclusters were synthesized by the implantation of carbon ions (C-) into thermally grown silicon dioxide film (-500 nm thick) on a Si (100) wafer and processed by high temperature thermal annealing. The carbon ions were implanted with an energy of 70 keV at a fluence of 5 x 10(17) atoms/cm2. The implanted samples were annealed at 1100 degrees C for different time periods in a gas mixture of 96% Ar+4% H2. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM) were used to study the structural properties of both the as-implanted and annealed samples. HRTEM reveals the formation of nanostructures in the annealed samples. The Raman spectroscopy also confirms the formation of carbon nano-clusters in the samples annealed for 10 min, 30 min, 60 min and 90 min. No Raman features originating from the carbon-clusters are observed for the sample annealed further to 120 min, indicating a complete loss of implanted carbon from the SiO2 layer. The loss of the implanted carbon in the 120 min annealed sample from the SiO2 layer was also observed in the XPS depth profile measurements. Room temperature photoluminescence (PL) spectroscopy revealed visible emissions from the samples pointing to carbon ion induced defects as the origin of a broad 2.0-2.4 eV band, and the intrinsic defects in SiO2 as the possible origin of the -2.9 eV bands. In low temperature photoluminescence spectra, two sharp and intense photoluminescence lines at -3.31 eV and -3.34 eV appear for the samples annealed for 90 min and 120 min, whereas no such bands are observed in the samples annealed for 10 min, 30 min, and 60 min. The Si nano-clusters forming at the Si-SiO2 interface could be the origin of these intense peaks.     

Si-rich a-SiC:H thin films: Structural and optical transformations during thermal annealing

Amorphous hydrogenated silicon-rich silicon carbide (a-Si_0.8C_0.2:H) thin films were prepared by plasma enhanced chemical vapour deposition and were thermally annealed in a conventional resistance heated furnace at annealing temperatures up to 1100 °C. The annealing temperatures were varied and the samples were characterised with Auger electron spectroscopy, glancing incidence X-ray diffraction, Raman spectroscopy, Fourier transformed infrared spectroscopy, transmission electron microscopy and photoluminescence (PL) spectroscopy. As-deposited a-Si_0.8C_0.2:H thin films contain a large amount of hydrogen and are amorphous. When annealing the films, the onset of Si crystallisation appears at 700 °C. For higher annealing temperatures, we observed SiC crystallites in addition to the Si nanocrystals (NCs). The crystallisation of SiC correlates with the occurrence of a strong PL band, which is strongly reduced after hydrogen passivation. Thus PL signal originates from the SiC matrix. Si NCs exhibit no PL yield due to their inhomogeneous size distribution.     

常压化学气相沉积方法制备非晶硅薄膜及其光致发光性能研究

使用改进的常压化学气相沉积(APCVD)系统制备了非晶硅薄膜,测量了样品的光致发光特性,使用Raman光谱和X射线光电子能谱(XPS)谱测量了薄膜的微结构特征.样品在523 nm出现发光峰,Raman光谱和XPS谱表明制备的薄膜结构中存在富氧相和富硅相的分相现象,分析认为相界面的存在是产生发光的原因.Raman光谱分峰结果表明薄膜中存在纳米晶粒.     

Zinc oxide epitaxial thin film deposited over carbon on various substrate by pulsed laser deposition technique

Zinc Oxide (ZnO) is a promising candidate material for optical and electronic devices due to its direct wide band gap (3.37 eV) and high exciton binding energy (60 meV). For applications in various fields such as light emitting diode (LED) and laser diodes, growth of p-type ZnO is a prerequisite. ZnO is an intrinsically n-type semiconductor. In this paper we report on the synthesis of Zinc Oxide-Carbon (ZnO:C) thin films using pulsed laser deposition technique (PLD). The deposition parameters were optimized to obtain high quality epitaxial ZnO films over a carbon layer. The structural and optical properties were studied by glazing index X-ray diffraction (GIXRD), photoluminescence (PL), optical absorption (OA), and Raman spectroscopy. Rutherford backscattering spectroscopy (RBS), scanning electron microscopy with energy dispersive spectroscopy (SEMEDS) and atomic force microscopy (AFM) were employed to determine the composition and surface morphology of these thin films. The GIXRD pattern of the synthesized films exhibited hexagonal wurtzite crystal structure with a preferred (002) orientation. PL spectroscopy results showed that the emission intensity was maximum at -380 nm at a deposition temperature of 573 K. In the Raman spectra, the E2 phonon frequency around at 438 cm(-1) is a characteristic peak of the wurtzite lattice and could be seen in all samples. Furthermore, the optical direct band gap of ZnO films was found to be in the visible region. The growth of the epitaxial layer is discussed in the light of carbon atoms from the buffer layer. Our work demonstrates that the carbon is a novel dopant in the group of doped ZnO semiconductor materials. The introduction of carbon impurities enhanced the visible emission of red-green luminescence. It is concluded that the carbon impurities promote the zinc related native defect in ZnO.     

Deposition of silicon doped and pure hydrogenated amorphous carbon coatings on quartz crystal microbalance sensors for protein adsorption studies

In this study hydrogenated amorphous carbon films (a-C:H) and silicon doped hydrogenated amorphous carbon films (a-C:H:Si) with different hydrogen and silicon contents were deposited onto sensors of a quartz crystal microbalance with dissipation detection (QCM-D). The resulting films were investigated with regard to their structural and elemental compositions using Raman spectroscopy, elastic recoil detection analysis and Rutherford backscattering spectroscopy. Furthermore the surface free energy (SFE) of the films was determined using contact angle measurements. The polar part of SFE of the a-C:H:Si films was found to be adjustable by the silicon content in these films and increased by increasing amounts of silicon. Carbon films with a broad range of chemical composition showed similar structure and properties when deposited on QCM-D sensors as compared with the deposition on silicon wafers. Subsequently, the amorphous carbon coated QCM-D sensors were used to study the adsorption of human serum albumin. These QCM-D results were related to the surface properties of the films.     

GCr15钢等离子体基离子注入Ti和C混合层的XPS研究

用X射线光电子谱研究了GCr15轴承钢不平衡磁控溅射沉积Ti,继之等离子体基离子注入碳的等离子体基离子注入混合层的C ,Ti浓度深度分布及其化学结构。表明混合层的最表层为碳沉积层 ,其C 1s谱峰呈类金刚石特征 ,喇曼光谱肯定了这一特征。碳沉积层下面为C Ti混合区 ,Ti和C各以游离态和化合物态存在。混合层内Ti和C浓度沿层深连续变化 ,无突变区 ,在原Ti沉积层与基材轴承钢发生反冲增强扩散现象     

Nanoforests composed of ZnO/C core–shell hexagonal nanosheets: fabrication and growth in a sealed thermolysis reactor and optical properties

An efficient method was developed for fabricating a highly porous nanoforest structure composed of ZnO/C core–shell hexagonal nanosheets (HNSs). Compact thermolysis of zinc acetate dihydrate in a sealed bath reactor at 400 °C over 20 h yielded the nanoforest structures. A carbon shell layer coating was applied in situ during the growth of the ZnO nanosheet core. The structures, morphologies, growth processes, compositions, and binding characteristics of the ZnO/C core–shell HNS nanoforests were analyzed using multi-purpose high-performance X-ray diffraction (XRD), scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS) techniques. XRD and XPS results suggest the existence of oxygen vacancy defects in the core surface of ZnO/C core–shell. The ZnO/C core–shell HNS nanoforests exhibited strong absorption features from the visible to the near-IR region (400–1670 nm), and the nanoforest films showed high electrical conductivity.     

Chemical bond analysis of amorphous carbon films

Hydrogen-free carbon films with the various sp³ bond fractions between 83% and 40% were prepared by mass-separated ion beam deposition (MSIBD). These sp³ bond fractions were obtained by electron energy loss spectroscopy (EELS). Chemical bond analysis of these carbon films was performed by x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and Raman spectroscopy, and the comparison of these methods was examined. XPS C1s spectra of carbon films show two contributions at the energies of 284.5 and 285.5 eV, which are originated from sp²-bonds and sp³ bonds, respectively. The sp³ bond fractions obtained by XPS are in good agreement with the values given by EELS. The fine structure of AES spectra at the kinetic energy region between 245 and 265 eV reflects the sp³ bond fraction. AES spectra are changed from the diamond-like feature to the graphite-like one with decreasing the sp³ bond fraction. Raman spectra show two broad peaks of G band and D band, the ratio of two peak intensities is independent on the sp³ bond fraction of films. The shift of G peak position has a correlation with the sp³ bond fraction in the sp³ bond rich region.     

通过制备Ti/TiC和Si/SixNy过渡层在铜基体上沉积类金刚石膜的研究

将磁控溅射物理气相沉积（MS-PVD）和电子回旋共振-微波等离子体增强化学气相沉积（ECR—PECVD）技术相结合，在铜基体上通过制备两种不同的过渡层，成功地沉积了类金刚石膜。拉曼光谱结果分析表明，所制备的碳膜都具有典型的类金刚石结构特征。通过原子力显微镜对薄膜的微观形貌进行分析，采用纳米压痕测量薄膜的硬度和模量。并对Ti／TiC过渡层和Si／SixNy过渡层上沉积的类金刚石薄膜进行了研究对比。     

Annealing characteristics of Si doped amorphous silica films by rf sputtering

Si doped amorphous silica films were prepared by rf magnetron sputtering technique. As-deposited films which had relatively low Si dopant were annealed in inert atmosphere, and spectroscopic analyses were performed for as-deposited and all the annealed samples by infrared (IR) absorption, X-ray fluorescence analysis, X-ray photoelectron spectroscopy (XPS) and 29Si magic angle sample spinning nuclear magnetic resonance spectroscopy (29Si MAS-NMR). When the sample was annealed at 800°C, the IR absorption peak located at 1080 cm–1 shifted to slightly higher wave number. On the other hand, the decrease of Si clusters or Si–Si bonds in as-deposited film was deduced from X-ray fluorescence and XPS spectra for the sample annealed at 800°C. These annealing characteristics of the films prepared in this study were discussed based on the random bonding model of SiOx film, and the spectral variations with thermal annealing were interpreted by the rearrangement of Si and O atoms in as-deposited films, rather than the simple clustering of excess Si atoms.