用等离子体增强化学气相沉积技术制备类金刚石碳薄膜的摩擦磨损性能研究

利用射频-直流等离子体增强化学气相沉积技术在单晶硅衬底上沉积类金刚石碳薄膜,采用激光拉曼光谱仪和原子力显微镜对薄膜的结构和表面形貌进行表征,采用纳米压痕仪测定薄膜的硬度,并用UMT型微摩擦磨损试验机考察了薄膜在不同试验条件下的摩擦磨损性能.结果表明:所制备的类金刚石碳薄膜表面光滑致密且硬度较高;在干摩擦条件下与GCr15钢球或Al2O3球配副时显示出良好的减摩抗磨性能,摩擦系数较低,耐磨寿命较长,而在水润滑条件下同Al2O3球配副时发生灾难性磨损.     

Relatively low temperature synthesis of graphene by radio frequency plasma enhanced chemical vapor deposition

We present a simple, low-cost and high-effective method for synthesizing high-quality, large-area graphene using radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) on SiO₂/Si substrate covered with Ni thin film at relatively low temperatures (650 °C). During deposition, the trace amount of carbon (CH₄ gas flow rate of 2 sccm) is introduced into PECVD chamber and the deposition time is only 30 s, in which the carbon atoms diffuse into the Ni film and then segregate on its surface, forming single-layer or few-layer graphene. After deposition, Ni is removed by wet etching, and the obtained single continuous graphene film can easily be transferred to other substrates. This investigation provides a large-area, low temperature and low-cost synthesis method for graphene as a practical electronic material.     

Synthesis and Characterization of New Alumina and Titania-Containing Hybrid Network Ceramer Materials from Sol-Gel Processing

Transparent hybrid materials have been prepared by incorporating either an alumina or titania alkoxide sol with triethoxysilane end-capped polytetramethylene oxide (PTMO) oligomer. In order to avoid undesirable precipitation after the addition of water, a β-dicarbonyl ligand, ethyl acetoacetate, was used. Triethoxysilane endcapped polytetramethylene oxide with a molecular weight of 2000 (g/mol) was chosen to react with either the alumina or titania sol to demonstrate the features of the reaction scheme. The extent of reaction leading to network formation has been qualitatively followed by infrared spectroscopy. A series of solid films were prepared by varying the molar ratio of either aluminum tri(sec-butoxide) or titanium tetraisopropoxide to ethyl acetoacetate, and the weight fraction of alumina or titania to that of PTMO. The refractive index as well as the general structure-property behavior of these hybrid materials were studied.     

Microstructure of nickel nanoparticles embedded in carbon films: case study on annealing effect by micromorphology analysis

The presented study is aimed at analyzing the surface texture of amorphous hydrogenated carbon layers containing nickel nanoparticles (Ni‐NPs@a‐C:H) within their structure, which were deposited by Radio Frequency (RF) sputtering and RF‐Plasma Enhanced Chemical Vapor Deposition (RF‐PECVD) methods on glass substrates. Prepared films were then used as research material following their annealing at two different temperatures of 250 °C and 350 °C in an inert argon atmosphere. Series of height samples were taken with the help of atomic force microscopy (AFM) operating in a non‐contact mode and examined in order to determine their fractal characteristics. Raw AFM data were first plane‐fitted to remove the surface bow exhibiting the so‐called residual surface, and then numerically processed to calculate the Areal Autocorrelation Function (AACF), which was later used to compute the Structure Function (SF). The log–log plots of the latter served for calculation of fractal properties of surfaces under investigation, including fractal dimension D, and pseudo‐topothesy K. The analysis of 3‐D surface texture helps to understand their essential characteristics and their implications as well as graphical models and their implementation in computer simulation. Copyright © 2016 John Wiley & Sons, Ltd.     

TPR and XPS characterization of chromia–lanthana–zirconia catalyst prepared by impregnation and microwave plasma enhanced chemical vapour deposition methods

Chromia–lanthana–zirconia catalysts prepared by wet impregnation and microwave plasma enhanced chemical vapour deposition methods have been characterized by temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The impregnation procedure requires large amounts of solvent and calcination at high temperatures producing Cr⁶⁺ species. Unlike this, it is found that the microwave plasma enhanced chemical vapour deposition (PECVD) method predominantly produces Cr³⁺ species on zirconia-based supports. Moreover, it has been shown that the dispersion of chromium species deposited on zirconia-based support by the PECVD method is higher than the dispersion of those prepared by wet impregnation. Thus, the advantages of PECVD over the impregnation method consist in this case in preventing the use of large amounts of solvent and avoiding the primary formation of poisonous Cr⁶⁺ species as well as in enabling the deposition of chromium species with high dispersion on zirconia-based supports.     

Surface passivation of In0.83Ga0.17As photodiode with high-quality SiN layer fabricated by ICPCVD at the lower temperature

The surface passivation of low-temperature-deposited SiN_x films has been investigated in PIN type In_0.83Ga_0.17As photodiodes. In contrast to SiN_x films (330 °C) fabricated by PECVD (Plasma enhanced chemical vapor deposition), the low-temperature-deposited SiN_x films (75 °C) fabricated by ICPCVD (Inductively coupled plasma chemical vapor depositon) have a good effect on passivation of In_0.83Ga_0.17As photodiodes, which caused reductions of dark current as large as 2–3 orders of magnitude at the same test temperature 200 K. The effects of low-temperature-deposited SiN_x passivations with lowrate (∼16 nm/min) model were compared to the ones with highrate (∼100 nm/min) model. SiN_x films with lowrate model have a better effect on reducing dark current of the photodiodes. The different SiN_x films were studied by SIMS. The results show that the content of oxides in SiN_x layer fabricated by PECVD is 2 orders of magnitude more than that in SiN_x layer fabricated by ICPCVD which could be the reason that low-temperature-deposited SiN_x passivation leads to higher performance. Further, the dark current density of the photodiodes with lowrate-deposited SiN_x passivations does not show the dependence on the perimeter-to-area(P/A) of the junction.     

相变域硅薄膜材料的光稳定性

采用RF-PECVD技术，通过改变反应气体的硅烷浓度制备了一系列不同晶化率不掺杂的硅薄膜材料，研究了工艺变化对材料结构的影响及材料光电特性同微结构的关系.随后进行了光衰退试验，在分析光照前后光电特性变化规律的基础上，认为材料中的非晶成分是导致材料光电特性衰退的主要原因.在靠近过渡区非晶一侧的硅材料比普通非晶硅稳定，衰退率较少；高晶化率微晶硅材料性能稳定，基本不存在光衰退；在靠近过渡区微晶一侧的硅材料虽然不是完全不衰退，但相比高晶化率硅材料来说更适合制备高效微晶硅电池. 关键词： 射频等离子体增强化学气相沉积 硅薄膜 Staebler-Wronski(SW)效应 稳定性     

厚二氧化硅光波导薄膜制备及其特性分析

以硅烷和氧化二氮作为反应气体，采用等离子体增强化学气相沉积(PECVD)技术，不使用掺杂，在单晶硅衬底上制备了用于平面光波导的二氧化硅薄膜。研究了薄膜折射率和淀积速率与工艺参量之间的关系，通过棱镜耦合仪、傅里叶变换红外光谱、原子力显微镜等测试手段，分析了薄膜的结构和光学特性。结果表明，实验能快速生长厚二氧化硅薄膜，薄膜表面平整，颗粒度均匀，同时薄膜具有折射率精确可控和红外透射性能好的特点，非常适合制作光波导器件。     

Quantum states in fabricating poly-Si films

The quantum states are presented in these processions of fabricating poly-Si films. Amorphous silicon films prepared by PECVD has been crystallized by conventional furnace annealing (FA) and rapid thermal annealing (RTA), respectively. It is found that the thin films grain size present quantum states with the increasing of the gas flow ratios of SiH₄, H₂ mixture, substrate temperatures, frequency power, annealing temperature and time.