High-Pressure Plasma Deposition of a-C:H Films by Dielectric-Barrier Discharge

The fabrication of a-C:H films from methane has been performed using dielectric-barrier discharges at atmospheric pressure. The effect of combined-feed gas, such as carbon dioxide, carbon monoxide or acetylene on the formation of a-C:H films has been investigated. It has been demonstrated that the addition of carbon monoxide or acetylene into methane leads to a remarkable improvement in the fabrication of a-C:H films. The characterization of carbon film obtained has been conducted using FT-IR, Raman and SEM.

Structure and tribological properties of Si/a-C:H(Ag)multilayer film in stimulated body fluid

Si/a-C:H(Ag)multilayer films with different modulation periods are prepared to test their potential applications in human body.The composition,microstructure,mechanical and tribological properties in the simulated body fluid are investigated.The results show the concentration of Ag first decreases and then increases with the modulation period decreasing from 984 nm to 250 nm.Whereas the C content has an opposite variation trend.Notably,the concentration of Ag plays a more important role than the modulation period in the properties of the multilayer film.The a-C:H sublayer of the film with an appropriate Ag concentration(8.97 at.%)(modulation period of 512 nm)maintains the highest sp3/sp2 ratio,surface roughness and hardness,and excellent tribological property in the stimulated body fluid.An appropriate number of Ag atoms and size of Ag atom allow the Ag atoms to easily enter into the contact interface for load bearing and lubricating.This work proves that the Ag nanoparticles in the a-C:H sublayer plays a more important role in the tribological properties of the composite-multilayer film in stimulated body fluid condition.

Nanocomposite TiC/a-C：H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and mechanical property were investigated. Using XPS and TEM, the films were identified to be a-C：H film containing TiC nanometre grains （namely, the so-called nanocomposite structure）. The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film. The hardness of a-C：H film with Ti is enhanced to 34 G Pa~ while that of a-C：H film without Ti is about 12 G Pa, and the coherent strength is also obviously enhanced at the critical load of about 35N.

Optical Characterization of Amorphous Hydrogenated Carbon(a-C:H)Thin Films Prepared by Single RF Plasma Method

Methane （CH4） plasma was used to produce amorphous hydrogenated carbon （a- C：H） films by a single capacitively coupled radio frequency （RF） powered plasma system. The system consists of two parallel electrodes： the upper electrode is connected to 13.56 MHz RF power and the lower one is connected to the ground. Thin films were deposited on glass slides with different sizes and on silicon wafers. The influence of the plasma species on film characteristics was studied by changing the plasma parameters. The changes of plasma species during the deposition were investigated by optical emission spectroscopy （OES）. The structural and optical properties were analyzed via Fourier transform infrared （FTIR） spectroscopy, X-ray diffraction （XRD） and UV-visible spectroscopy, and the thicknesses of the samples were measured by a profilometer. The sp3/sp2 ratio and the existing H atoms play a significant role in the determination of the chemical properties of thin films in the plasma. The film quality and deposition rate were both increased by raising the power and the flow rate.

Method of measuring one-dimensional photonic crystal period-structure-film thickness based on Bloch surface wave enhanced Goos–H?nchen shift

This paper puts forward a novel method of measuring the thin period-structure-film thickness based on the Bloch surface wave(BSW) enhanced Goos–Hanchen(GH) shift in one-dimensional photonic crystal(1DPC). The BSW phenomenon appearing in 1DPC enhances the GH shift generated in the attenuated total internal reflection structure. The GH shift is closely related to the thickness of the film which is composed of layer-structure of 1DPC. The GH shifts under multiple different incident light conditions will be obtained by varying the wavelength and angle of the measured light, and the thickness distribution of the entire structure of 1DPC is calculated by the particle swarm optimization(PSO) algorithm.The relationship between the structure of a 1DPC film composed of TiO_(2) and SiO_(2) layers and the GH shift, is investigated.Under the specific photonic crystal structure and incident conditions, a giant GH shift, 5.1 × 10^(3) times the wavelength of incidence, can be obtained theoretically. Simulation and calculation results show that the thickness of termination layer and periodic structure bilayer of 1DPC film with 0.1-nm resolution can be obtained by measuring the GH shifts. The exact structure of a 1DPC film is innovatively measured by the BSW-enhanced GH shift.

Effect of Chromium on Structure and Tribological Properties of Hydrogenated Cr/a-C:H Films Prepared via a Reactive Magnetron Sputtering System

Hydrogenated Cr-incorporated carbon films （Cr/a-C：H） are deposited successfully by using a dc reactive mag- netron sputtering system. The structure and mechanical properties of the as-deposited Cr/a-C：H films are characterized systematically by field-emission scanning electron microscope, x-ray diffraction, Raman spectra, nanoindentation and scratch. It is shown that optimal Cr metal forms nanocrystalline carbide to improve the hardness, toughness and adhesion strength in the amorphous carbon matrix, which possesses relatively higher nano-hardness of 15. 7 CPa, elastic modulus of 126.8 GPa and best adhesion strength with critical load （Lc） of 36 N for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm. The friction and wear behaviors of as-deposited Cr/a-C：H films are evaluated under both the ambient air and deionized water conditions. The results reveal that it can achieve superior low friction and anti-wear performance for the Cr/a-C：H film deposited at CH4 flow rate of 20sccm under the ambient air condition, and the friction coetllcient and wear rate tested in deionized water condition are relatively lower compared with those tested under the ambient air condition for each film. Superior combination of mechanical and tribological properties for the Cr/a-C：H film should be a good candidate for engineering applications.

a-C∶F∶H films prepared by PECVD

Fluorinated amorphous hydrogenated a-C∶F∶H carbon thin films were deposited using radio frequency plasma enhanced chemical vapor deposition（RF-PECVD） reactor with CF4 and CH4 as source gases and were annealed in a N2 atmosphere. The properties of these films were evaluated by FTIR spectrometry, UV-VIS spectrophotometry and single-wavelength spectroscopic ellipsometry. A correspondence relativity connection between the deposition rate and technology was found. The chemical bonding structures and the content of CHx and CFx in the films are transformed and the optical band gap decreases monotonically with increasing temperature after annealing. The dielectric constant is increased with decreasing content of F in the films and the optical band gap is decreased with decreasing the content of H in the film.

Rare earth Ce-modified (Ti,Ce)/a-C:H carbon-based film on WC cemented carbide substrate

WC cemented carbide suffers severe wear in water environments. A novel carbon-based film could be a feasible way to overcome this drawback. In this study, a rare earth Ce-modified（Ti,Ce）/a-C：H carbon-based film is successfully prepared on WC cemented carbide using a DC reactive magnetron sputtering process. The microstructure, mechanical properties,and tribological behavior of the as-prepared carbon-based film are systematically investigated. The results show that the doping Ti forms Ti C nanocrystallites that are uniformly dispersed in the amorphous carbon matrix, whereas the doping Ce forms CeO2 that exists with the amorphous phase in the co-doped（Ti,Ce）/a-C：H carbon-based film. The mechanical properties of this（Ti,Ce）/a-C：H film exhibit remarkable improvements, which could suggest higher hardness and elastic modulus as well as better adhesive strength compared to solitary Ti-doped Ti/a-C：H film. In particular, the as-prepared（Ti,Ce）/a-C：H film presents a relatively low friction coefficient and wear rate in both ambient air and deionized water,indicating that（Ti,Ce）/a-C：H film could feasibly improve the tribological performance of WC cemented carbide in a water environment.

Deposition of a-CN_x:H Films Using Uniform Supermagnetron Plasma under a Stationary Magnet Field

By generating closed-loop electron E × B drift over the front and back surface of a band magnetron cathode, a uniform magnetron plasma can be formed over the front surface. Here, we attempted to generate a uniform supermagnetron plasma under a stationary magnetic field by situating two such band magnetron cathodes face-to-face in parallel. Performing uniform supermagnetron plasma chemical vapor deposition (CVD) with tetraethylorthosilicate (TEOS)/O2 CVD, SiO2 films with good uniformity (±5%) at the central region of the cathode could be achieved under a stationary magnetic field of about 160 G. Using this supermagnetron plasma CVD apparatus, a-CNx:H films were then deposited to investigate their characteristics using isobutane (i-C4H10)/N2 mixed gases. A relatively high deposition rate of about 100 nm/min was obtained. The a-CNx:H films obtained had a hardness of about 25 GPa, higher than that of glass (22 GPa).

Pulsed Supermagnetron Plasma CVD of a-CN_x:H Electron-Transport Films for Au/a-CN_x:H/p-Si Photovoltaic Cells

Hydrogenated amorphous carbon nitride (a-CNx:H) films were formed on p-Si wafers set on a lower elec-trode by pulsed supermagnetron plasma CVD using i-C4H10 and N2 gases. Lower electrode RF power (LORF) of 13.56 MHz (50 - 800 W) was modulated by a 2.5-kHz pulse at a duty ratio of 12.5%, and upper electrode RF power (UPRF) of 50 - 400 W was supplied continuously. The optical band gap decreased with an increase in LORF at each UPRF. The open circuit voltage of Au/a-CNx:H/p-Si photovoltaic cells (a-CNx:H film thickness: 25 nm) was about 200 mV for each cell, and the short circuit current density and energy conversion efficiency increased with LORF for each UPRF. The highest energy conversion efficiency of 0.81% was obtained at UPRF/LORF of 200/800 W.

退火温度对a-C:H膜结构及摩擦学性能的影响

为研究环境温度对含氢无定形碳(a-C:H)膜结构和性能的影响,将a-C:H膜在大气环境中进行高温退火处理,并借助红外光谱、拉曼光谱、X射线光电子能谱、3D表面分析仪和球盘摩擦试验机等手段对退火前后a-C:H膜的结构、组成和性能进行了系统地考察.研究发现,在较低的退火温度下(300℃),a-C:H膜结构无明显变化,而其内应力降低,摩擦学性能显著提高;在400℃和500℃下退火,膜结构发生明显变化并伴随严重氧化,同时摩擦学性能降低甚至完全失效.结果表明,退火温度的选择对a-C:H膜的结构、组成及性能具有重要影响.

a-C∶H膜在不同真空度下的摩擦学行为研究

采用非平衡磁控溅射技术在不锈钢及Sip(111)基体上制备了含氢无定形碳(a-C∶H)薄膜,沉积的薄膜表面光滑,硬度高,内应力小,膜/基结合力好。利用球-盘摩擦实验机对薄膜在不同真空度(1.0×105、5.0×10-2、1.0×10-2、5.0×10-3 Pa)下的摩擦学行为进行了研究,结果表明,随着真空度的升高,薄膜的摩擦系数逐渐减小,磨损率逐渐增大。在5.0×10-3 Pa时,a-C∶H膜的摩擦学行为发生突变,此时薄膜的摩擦系数为0.005,而耐磨寿命很短。高真空中,薄膜寿命的突变可能与薄膜脱氢而结构发生变化有关。

中频磁控溅射制备a-C∶H(Al,W)薄膜及其性能研究

采用中频磁控溅射技术，以w、Al复合靶（面积比为1：1）为靶材，在氩气和甲烷混合气体中于iq（100）型单晶硅表面沉积了一系列Al、w共掺杂含氢非晶碳[a-c：H（Al，w）]薄膜．分析了不同甲烷流量对薄膜成分、结构和表面形貌的影响，并表征了薄膜的力学性能和摩擦磨损行为．结果表明：随着甲烷流量的增加，薄膜中C含量呈上升趋势，而w和Al含量均呈现递减趋势，过高流量的CH。会导致金属靶材中毒．薄膜中的sp^2C和sp^3c含量受w、Al以及H注入效应的共同影响．所制备的薄膜表面均较为平滑，表面粗糙度（RMS）在0．39～0．48nm范围内．薄膜的纳米硬度（日）在9．98-11．37GPa之间，弹性模量（E）介于71～93．36GPa之间，弹性恢复系数均在70％以上．当薄膜中w和Al的原子百分含量分别为3．74％和2．37％时，H／E值和H^3／E^3值分别为0．141和0．198，且此时薄膜在大气环境下表现出较好的减摩抗磨性能．薄膜具有适度的sp^3C／sp^2c比值、优异的弹性形变性能、摩擦过程中对偶球表面形成连续而致密的转移层等因素是薄膜具有良好摩擦学性能的重要原因．

a-C∶H/a-Se复合膜晶化分形凝聚的计算机模拟研究

本文基于红外透射及喇曼谱分析的结果提出了一个 a-C:H/a-Se 复合膜的 a-C∶H 层非平衡晶化凝聚模型,并做了计算机模拟研究。模拟得到的图形是具有良好的无标度性的链环状分形。其分维值为1.37±0.02,此结果得到了实验的肯定。这对非晶膜的结构及晶化机理的研究均富有价值。

γ辐照对a-C:H薄膜微观组织、力学性能及摩擦学性能的影响

近年来随着核能及其核装备的发展,辐照环境下高能粒子对润滑材料服役行为的影响受到越来越多的关注.本研究利用自行设计研制的磁控溅射系统制备a-C:H润滑薄膜,并对其进行伽马(γ)辐照处理.考察γ辐照康普顿效应对a-C:H薄膜微观组织、力学性能和摩擦学性能的影响.结果表明:经γ辐照后a-C:H薄膜存在由sp^(2)杂化C原子结构向sp^(3)杂化C原子结构转变的趋势,且辐照使得C-H键发生断裂,薄膜内H原子的键合能降低.伽马辐照使得aC:H薄膜的纳米机械性能显著提高,辐照样品的残余应力也随辐照剂量呈增加趋势.此外,γ辐照也使得a-C:H薄膜的摩擦系数和磨损率轻微增加.综合分析可知,γ辐照在测试剂量范围内对a-C:H薄膜的摩擦性能影响有限,但辐照诱发应力的增加是限制其在核环境中应用的主要因素.

a-C:N:H纳米尖端荧光产生的机理

用CH4,H2和NH3为反应气体,利用等离子体增强热丝化学气相沉积在沉积有碳膜的Si衬底上制备了a-C:N:H纳米尖端,并用扫描电子显微镜和微区Raman光谱仪对碳膜和纳米尖端进行了表征。结果表明:Raman谱中含有与碳和氮相关的峰,且纳米尖端的Raman谱比碳膜的Raman谱有很强的荧光背景。Raman谱中的峰说明沉积的碳膜和纳米尖端是a-C:N:H薄膜和a-C:N:H尖端。a-C:N:H纳米尖端的Raman谱中强荧光背景的产生表明其在激发光源照射的过程中发射了强荧光,对a-C:N:H纳米尖端产生强荧光的机理进行了探讨。

直流反应磁控溅射沉积a-C:H薄膜的微结构和摩擦磨损行为

采用直流的反应磁控溅射技术,以高纯石墨为溅射靶材和CH_4为反应气体,调节CH_4流量,在p(100)单晶硅和不锈钢基底上成功制备出系列的含氢a-C:H薄膜.利用场发射扫描电子显微镜(FESEM)、原子力显微镜(AFM)、Raman光谱、纳米压痕仪、CSM划痕测试仪、摩擦磨损试验机等测试手段对所制备含氢a-C:H薄膜的微结构、力学性能和摩擦磨损行为进行系统表征.结果表明:随着CH_4流量的增加,含氢a-C:H薄膜的致密度呈现出微弱的先增加后减小的趋势;薄膜的沉积速率随着CH_4流量的增加逐渐增加,但增幅呈现出逐渐减小趋势;随着CH_4流量的增加,薄膜中sp^3杂化键含量及其纳米硬度和杨氏模量也呈现出先增加后减小的规律;摩擦实验结果表明当CH_4流量为8 sccm,所制备的含氢a-C:H薄膜的摩擦学性能最佳,摩擦系数为0.20,磨损率为6.48×10^(-7)mm^3/(N·m).

Growth Rate of a-Si∶H Film Influenced by Magnetic Field Gradient in MWECR CVD Plasma System

The magnetic field profiles,which are produced by three ways in the deposition chamber and plasma chamber of single coil divergent field MWECR CVD system,are investigated.The magnetic field gradient of these magnetic field profiles is obtained quantitatively by using Lorentz fit.The results indicate that the gradient value of the magnetic field profile near by the substrate,which is produced by a coil current with 137.7A if a SmCo permanent magnet is equipped under the substrate holder,is the largest;when the SmCo permanent magnet is taken away,the larger one is produced by the coil current with 137.7A and the smallest one produced by a coil current with 115.2A.High deposition rate of a-Si∶H film is observed near by the substrate with high magnetic field gradient.But uneven deposition rate along the radius of the sample holder is also found by infrared analysis technology when sample is deposited in magnetic field profile,which is produced by the coil current with 137.7A if the SmCo permanent magnet is equipped under the substrate holder.

rf-dc PECVD制备的a-C∶H(N)薄膜的结构分析

采用射频－直流等离子增强化学气相沉积技术用Ｃ２Ｈ２和Ｎ２气的混合气体制备出ａ－Ｃ∶Ｈ（Ｎ）薄膜，用ＴＥＭ、红外谱、ＸＰＳ等多种分析测试手段研究了薄膜的结构。结果表明ａ－Ｃ∶Ｈ（Ｎ）薄膜中Ｎ与Ｃ原子可形成ＮＣ、ＣＮ和ＮＣ键，而碳氢原子主要以ＣＨ２基的形式存在。且薄膜中存在具有理想化学配比的Ｃ３Ｎ４相。

不锈钢表面防护TiC/a-C∶H纳米复合薄膜的耐腐蚀性能

采用直流反应磁控溅射技术在304不锈钢表面沉积TiC/a-C∶H纳米复合薄膜,并研究了TiC/a-C∶H纳米复合薄膜对不锈钢耐腐蚀性能的影响。通过扫描电子显微镜(SEM)和原子力显微镜(AFM)观察,结果表明薄膜表面光滑且薄膜结构均匀致密。Raman光谱和XRD测试结果表明,薄膜具有纳米晶TiC镶嵌非晶碳基质的典型纳米复合微结构。通过测量薄膜的静态接触角分析薄膜的润湿性,不锈钢表面沉积TiC/a-C∶H纳米复合薄膜后疏水性能明显提高,水接触角高达98°。电化学腐蚀测试结果表明,不锈钢表面沉积TiC/a-C∶H纳米复合薄膜体系在质量分数为3.5%的NaCl溶液中自腐蚀电位约为-0.09V,腐蚀电流密度为2.43×10-8 A·cm-2,与无薄膜防护的裸露不锈钢相比,其耐腐蚀性能得到明显改善。