影响金刚石薄膜生长因素的研究

本文用ＨＦＣＶＤ法对在硬质合金衬底上生长金刚石薄膜的诸多影响因素，如衬底的预处理、碳源浓度和热丝及衬底温度等进行了系统地研究并最终找出在该衬底上生长金刚石薄膜的最佳生长条件。     

氮原子在CVD低压金刚石制备过程中的作用

根据理论计算得到了碳氢氮体系低压金刚石生长非平衡定态相图，结果与实验数据相当符合，并通过相图和热力学计算讨论了氮原子含量对金刚石生长条件的影响以及在ＣＶＤ金刚石制备过程中提高金刚石薄膜生长速率的原因。     

WC和Si衬底生长金刚石薄膜的研究

采用ＳＥＭ,Ｒａｍａｎ光谱等手段,较全面系统地研究了ＨＦＣＶＤ法在ＷＣ和Ｓｉ衬底上生长金刚石薄膜时,衬底预处理、碳源深度、热丝及衬底温度等对金刚石形核、生长的影响。并对两种衬底进行了对比与分析,最后总结出影响金刚石形核密度、形核速率、晶形结构及晶形完善性的关键因素。     

Al2O3陶瓷上沉积金刚石薄膜的研究

以酒精为碳源，用热丝ＣＶＤ法对不同表面状态的Ａｌ２Ｏ３衬底进行了金刚石薄膜沉积的比较，用扫描电镜，喇曼光谱和Ｘ射线衍射等方法检测了沉积出的金刚石膜的质量，并讨论了它们对成核和生长的影响。     

金刚石材料的摩擦及磨损

研究了金刚石单晶，以钴和碳化硅作粘结剂的金刚石聚晶及ＣＶＤ金刚石薄膜被软磨头摩擦和磨损的行为。在正压力和摩擦产生的拉应力聚合作用下，单道次摩擦时，ＴｉＢ２磨头可以使金刚石单昌表面产生“人字形”裂纹，我道次摩擦时，裂纹搭接及碎块脱落使金刚石表面产生磨痕。类似的磨痕也产生在聚晶金刚石表面。铝合金及中碳钢磨头可以较显著地磨损ＣＶＤ金刚石薄膜。     

钼片上CVD金刚石膜的界面研究

借助金相显微镜，ＳＥＭ、ＥＤＸＡ对钼片上ＣＶＤ金刚石膜的界面形貌和成分进行了研究，对比了加磁场与不加磁场所沉积的金刚石膜的横民面形态特征，结果表明：加磁场与否在ＣＶＤ金刚石膜和钼基体之间均存在数μｍ厚的Ｍｏ２Ｃ中间层，它呈细小柱状昌方式生长，该层以下的钼基体发生了再结晶细化；加磁场沉积的金刚石膜较致密，（显微）空隙数量较小、金刚石颗粒尺寸较小、金刚石膜背面粘附较多的Ｍｏ２Ｃ聚集物。压痕试验法评定的     

CVD金刚石薄膜取向生长研究现状

单晶衬底上外延生长金刚石薄膜一直是ＶＣＤ金刚石技术领域的重要研究方向之一,近年来这方面的研究取得了长足的进步。回顾了金刚石取向膜的研究史,介绍了提高金刚石膜取向度的方法和目前对金刚石取向膜生长过程,生长机理研究取得的进展及金刚石取向膜具有独特优异性能的实验研究。     

原位光发射谱研究横向偏压金刚石薄膜生长过程

利用热丝ＣＶＤ方法研究了横向偏压对金刚石薄膜成核和生长的影响．实验表明,随着偏流的增加,金刚石在光滑硅衬底上的成核密度得到显著提高,最高可达 １．１×１０^８ｃｍ^－２,但是横向偏压不利于金刚石薄膜的生长．原位光发射谱研究发现,横向偏流的增加提高了原子氢和ＣＨ基团的浓度,导致衬底表面非晶碳层的形成,这可能是造成横向偏压促进金刚石成核却不利于金刚石薄膜生长的主要原因．     

CVD金刚石薄膜的介电性能研究

对直流电弧等离子体ＣＶＤ制备的金刚石薄膜的介电性能进行了研究，结果表明，金刚石薄膜的介电性能主要取决于样品的多昌性质以及表面和晶界处的非金刚石相和杂质成分。     

CVD金刚石成核的最新研究

研究了化学气相条件下金刚石在非均匀研磨硅基底表面及镜面基底和均匀研磨基底边缘及角域处的成核行为。发现ＣＶＤ金刚石成核不仅依赖于沉积区缺陷，更主要由缺陷的锐度决定，即缺陷加强ＣＶＤ金刚石成核的锐度效应。在对无序碳上ＣＶＤ金刚石成核研究的基础上，讨论了ＣＶＤ金刚石成核的机理，并由此阐明了各种表面预处理及负偏压等增强ＣＶＤ金刚石成核的微观过程。     

Simultaneous fabrication of nanocrystalline and {100} textured large-grained diamond films

In this work, we report the simultaneous synthesis of both nanocrystalline and {100} textured large-grained diamond films in one deposition run performed in a 5-kW microwave plasma chemical vapor deposition (MPCVD) reactor. This was achieved by employing the coupled effect of nitrogen addition in the gas phase and substrate temperature on the growth of diamond films. In one deposition run, different substrate surface temperatures were obtained by a novel substrate arrangement, nanocrystalline diamond of high growth rate around 3 μm/h was formed at low temperature, while {100} textured large-grained diamond of much higher growth rate about 11 μm/h was grown at high temperature. This new method opens way for mechanical and tribological applications of both nano-diamond and {100} textured diamond in industrial level. This result indicates that distinct growth modes or growth mechanisms were involved at different substrate temperatures with a certain amount of nitrogen addition. The coupled effect of nitrogen addition and temperature on the growth of CVD diamond films and the involved growth mechanism is briefly discussed from the point of view of gas phase chemistry and surface reactions.     

金刚石薄膜的性质、制备及应用

金刚石有着优异的物理化学性质，化学气相沉积金刚石薄膜的研究受到研究人员和工业界的广泛关注。通过评述金刚石薄膜的性质、制备方法及应用等方面的研究成果，着重阐述化学气相沉积金刚石薄膜技术的基本原理，分析了各种沉积技术的优、缺点。结合对金刚石薄膜应用的讨论，分析了金刚石薄膜在工业应用中存在的问题和制备技术的发展方向。分析结果表明：MWCVD法是高速率、高质量、大面积沉积金刚石薄膜的首选方法；而提高金刚石的生长速度、降低生产成本等是进一步开发刚石薄膜工业化应用所需解决的主要问题。     

A comparative study of p-type diamond films using Raman and transport measurements

The influence of deposition temperature in the properties of synthetic diamond films grown by two different chemical vapor deposition (CVD) techniques, hot-filament- and microwave-plasma-assisted, was investigated. These samples were obtained using the optimal growth conditions previously achieved in this work. Raman spectroscopy was employed in order to investigate the diamond film quality as a function of the deposition temperature. It was found that the nondiamond carbon bands decrease as the deposition temperature increases for both the deposition methods, leading to higher-quality diamond films. The micro- and macro-Raman spectra showed that the nondiamond band is already present in a single diamond grain. Both techniques provided well homogeneous diamond films and with equivalently good quality. Boron-doped diamond films with different carrier concentration levels were also studied. In order to get details about the electrical properties of the films, resistivity as a function of the boron concentration—in association with Raman spectra—and temperature-dependent transport measurements were employed. The results showed that the boron doping is the main responsible for the conductivity and that the variable range hopping (VRH) mechanism dominates the transport in these doped diamond films.     

Deposition of Diamond Films in a Closed Hot Filament CVD System

A closed system hot filament chemical vapor deposition (CVD) reactor has been used to deposit diamond films on silicon substrates. A fixed charge of hydrogen gas is fed into the deposition system until the desired deposition pressure level is reached. A solid graphite cylindrical rod held above the tungsten filament was the carbon source. System parameters for diamond film growth have been determined. The diamond structure of the films has been verified by x-ray diffraction (XRD). Morphology typical of CVD diamond films has been observed in scanning electron microscopy (SEM). The quality of the diamond films has been evaluated by micro-Raman spectroscopy.     

Tuning the conditions for the deposition of nanocrystalline diamond by hot filament chemical vapour deposition

Although large focus has been placed into the deposition of nanocrystalline and ultra-nanocrystalline diamond films, most of this research uses microwave plasma assisted CVD systems. However, the growth conditions used in microwave systems cannot be directly used in hot-filament CVD systems. This paper, aims to enlarge the knowledge of the diamond film depositing process. H2/CH4/Ar gas mixtures have been used to deposit micro, nano and ultra-nanocrystalline diamond films by hot-filament CVD systems. Additionally, the distance between the filaments array and the substrate was varied, in order to observe its effect and consequently the effect of a lower substrate temperature in the nucleation density and deposition. All the samples were characterized for microstructure and quality, using scanning electron microscopy and Raman spectroscopy.     

Optimization of chemical vapor deposition diamond films growth on steel: correlation between mechanical properties, structure, and composition

In the present work we perform optimization of mechanical and crystalline properties of CVD microcrystalline diamond films grown on steel substrates. A chromium-nitride (Cr-N) interlayer had been previously proposed to serve as a buffer for carbon and iron inter-diffusion and as a matching layer for the widely differing expansion coefficients of diamond and steel. However, adhesion and wear as well as crystalline perfection of diamond films are strongly affected by conditions of both Cr-N interlayer preparation and CVD diamond deposition. In this work we assess the effects of two parameters. The first one is the temperature of the Cr-N interlayer preparation: temperatures in the range of 500 degrees C-800 degrees C were used. The second one is diamond film thickness in the 0.5 microm-2 microm range monitored through variation of the deposition time from approximately 30 min to 2 hours. The mechanical properties of so deposited diamond films were investigated. For this purpose, scratch tests were performed at different indentation loads. The friction coefficient and wear loss were assessed. The mechanical and tribological properties were related to structure, composition, and crystalline perfection of diamond films which were extensively analyzed using different microscopic and spectroscopic techniques. It was found that relatively thick diamond film deposited on the Cr-N interlayer prepared at the temperature similar to that of the CVD process has the best mechanical and adhesion strength. This film was stable without visible cracks around the wear track during all scratch tests with different indentation loads. In other cases, cracking and delamination of the films took place at low to moderate indentation loads.     

Developments in synthesis, characterization, and application of large, high-quality CVD single crystal diamond

Single crystal diamond synthesis by microwave plasma chemical vapor deposition at rapid growth rate has considerably advanced in the past few years. Developments have been made in growth, optical quality, and mechanical properties. Of the various types of single crystal diamond that can be produced using these techniques, high quality single crystal CVD diamond can be routinely produced, and this material is playing an increasing role in research on materials under extreme conditions. This article highlights recent developments in single crystal CVD diamond synthesis and characterization, as well as various applications in high-pressure materials research.     

Implementation of the time-modulated process to produce diamond films using microwave-plasma and hot-filament CVD systems

A newly developed process called time-modulated chemical vapour deposition (TMCVD) was employed to deposit smooth polycrystalline diamond films onto silicon substrates using both microwave plasma CVD (MPCVD) and hot-filament CVD (HFCVD) systems. The distinctive feature of the TMCVD process, which separates it from the conventional diamond CVD process, is that it pulses methane (CH₄) at different flow rates for different time durations into the vacuum reactor during the entire diamond CVD process. Generally, both MPCVD and HFCVD systems produced results that displayed similar trends, except that the growth rate results obtained using the two CVD systems were conflicting. In comparison to the conventional CVD diamond films, the time-modulated films, deposited using both MPCVD and HFCVD techniques, were generally found to be (i) smoother, (ii) consisted of smaller diamond crystallites and (iii) displayed approx. similar film quality. The diamond-carbon phase purity of the as-grown films was assessed using Raman spectroscopy. In addition, the surface roughness, Ra, values of the deposited films were obtained using surface profilometry.     

大面积高光学质量金钢石自支撑膜的制备

介绍了一种新型的磁控/流体动力学控制的大口径长通道直流电弧等离子体炬，并据此设计建造了100千瓦级高功率DC Arc Plasma Jet CVD金刚石膜沉积系统，讨论了该系统采用的半封闭式气体循环系统的工作原理，以及在气体循环条件下制备大面积高光学质量金刚石自支撑膜的研究结果。     

微波CVD金刚石热沉片的制备研究

采用化学气相沉积法（CVD）制备的金刚石薄膜具有接近于天然金刚石的导热性能,是目前最为理想的热沉材料。利用微波等离子体化学气相沉积法（MPCVD）制备了金刚石热沉片,并在此基础上研究了不同沉积工艺对金刚石热沉片散热性能的影响。采用扫描电子显微镜（SEM）和激光拉曼光谱（Raman）检测了薄膜的表面形貌及纯度,金刚石热沉片的导热性能则通过测量封装LED后薄膜的散热效果来进行表征。结果表明,在其他条件不变的情况下,提高生长过程中的微波输出功率、降低反应气压以及增加基片温度有利于制备出散热性能更佳的金刚石热沉片。