Effect of Hot Isostatic Pressing on the Elastic and Optical Properties of Polycrystalline CVD ZnS

Hot isostatic pressing (HIP) is shown to increase the Young's modulus and transmittance of polycrystalline zinc sulfide produced by chemical vapor deposition. Both effects are associated with the decrease in the relative volume of nonequilibrium crystallite boundaries containing dangling bonds, which are responsible for the formation of bound surface charges, leading to interfacial polarization. The secondary recrystallization induced by HIP leads to the formation of thin, equilibrium grain boundaries.     

氢等离子作用下Fe、Co对金刚石膜刻蚀的研究

金刚石具有很高的硬度,加工困难,为寻找一种刻蚀效率较高的材料,利用微波等离子体化学气相沉积（MPCVD）技术,在氢等离子体作用下,研究了Fe、Co对CVD金刚石膜表面的刻蚀效率。用SEM观察刻蚀效果,用Raman光谱对其表面结构进行表征。结果表明：在氢等离子体的作用下,Fe、Co对金刚石表面都有明显的腐蚀作用,其中Fe的刻蚀速率较高,并且可以通过对溶碳材料的厚度控制,来实现对刻蚀速率与刻蚀量的有效控制。对刻蚀后的样品用混合酸及丙酮处理后,得到了可与原始金刚石相媲美的质量。     

Field emission property of hydrogenated chemical vapor deposited diamond films studied by scanning tunneling microscopy

By using scanning tunneling microscopy, the plots of tunneling current versus applied voltage, at the local points for hydrogenated and oxygenated chemical vapor deposited diamond films, were investigated. For comparison, the measurement points were adopted on the centers of the crystalline grains and at the grain boundaries, respectively. The results indicated that, for the hydrogenated chemical vapor deposited diamond, the field emission character is much better on the center of the crystalline grains than at the grain boundary. In contrast, for the oxygenated samples, the crystalline grains show a poor field emission character. The two diamond surfaces exhibit similar field emission characters at the grain boundaries. The surface emission mechanisms of the hydrogenated chemical vapor deposited diamond films were also discussed.     

Correlation between diamond grain size and hydrogen incorporation in nanocrystalline diamond thin films

Hydrogen-incorporated nanocrystalline diamond thin films have been deposited in microwave plasma enhanced chemical vapour deposition (CVD) system with various hydrogen concentrations in the Ar/CH₄ gas mixture. The bonding environment of carbon atoms was detected by Raman spectroscopy and the hydrogen concentration was determined by elastic recoil detection analysis. Incorporation of H₂ species into Ar-rich plasma was observed to markedly alter the microstructure of diamond films. Raman spectroscopy results showed that part of the hydrogen is bonded to carbon atoms. Raman spectra also indicated the increase of non-diamond phase with the decrease in crystallite size. The study addresses the effects of hydrogen trapping in the samples when hydrogen concentration in the plasma increased during diamond growth and its relation with defective grain boundary region.     

Microstructures of microcrystalline silicon thin films prepared by hot wire chemical vapor deposition

Undoped hydrogenated microcrystalline silicon (μc-Si:H) thin films were prepared at low temperature by hot wire chemical vapor deposition (HWCVD). Microstructures of the μc-Si:H films with different H₂/SiH₄ ratios and deposition pressures have been characterized by infrared spectroscopy X-ray diffraction (XRD), Raman scattering, Fourier transform (FTIR), cross-sectional transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). The crystallization of silicon thin film was enhanced by hydrogen dilution and deposition pressure. The TEM result shows the columnar growth of μc-Si:H thin films. An initial microcrystalline Si layer on the glass substrate, instead of the amorphous layer commonly observed in plasma enhanced chemical vapor deposition (PECVD), was observed from TEM and backside incident Raman spectra. The SAXS data indicate an enhancement of the mass density of μc-Si:H films by hydrogen dilution. Finally, combining the FTIR data with the SAXS experiment suggests that the Si---H bonds in μc-Si:H and in polycrystalline Si thin films are located at the grain boundaries.     

用氢气/甲醇混合气体在微波等离子体CVD中合成纳米晶粒金刚石膜

用微波等离子体增强化学气相沉积方法(MPECVD),利用氢气和甲醇的混合气体,在硅片上沉积出纳米晶粒的金刚石薄膜.用扫描电子显微镜(SEM)、拉曼光谱(Raman)、原子力显微镜(AFM)及扫描隧道显微镜(STM)对薄膜的晶粒平面平整性及纯度进行了表征.通过SEM发现,提高甲醇浓度或降低沉积温度可以减小金刚石膜的晶粒尺寸.拉曼光谱显示薄膜中确实存在纳米晶粒的金刚石,并且薄膜的主要成分为金刚石.用AFM测得薄膜表面的粗糙度Rms＜80m,STM观测晶粒的平均尺寸在10～20m之间.研究结果表明,用MPECVD方法,利用氢气和甲醇的混合气体是制备纳米晶粒金刚石膜的一种理想方法.     

氢和硼离子轰击可消除(001)面多晶金刚石膜的空位缺陷

在微波等离子体化学气相沉积金刚石膜时,采用负偏压使氢和硼离子轰击金刚石膜表面。发现单纯的氢离子的轰击会导致表面刻蚀,可使（001）面颗粒尺寸增大,用扫描电镜（SEM）和阴极发射光谱（CL）分析了硼离子掺杂后[001]取向的金刚石膜表面,发现CL中A峰消失,表明薄膜中位错密度降低,首次发现CL谱中741.5nm峰和575nm到625nm宽峰明显下降,表明在金刚石膜中,中性空位和氮空位缺陷基本消失,利用小原子穿透理论解释了这个现象。     

CVD金刚石膜的场发射机制

利用热灯丝化学气相沉积方法在光滑的钼上沉积了金刚石膜,用扫描电子显微镜和Raman谱对金刚石膜进行了分析。结果表明金刚石膜是由许多金刚石晶粒组成,晶粒间界主要是石墨相,并且在膜内有许多缺陷。金刚石膜的场发射结果表明高浓度CH4形成的金刚石膜场发射阈位电场较低浓度CH4形成的金刚石为低。这意味着杂质（如石墨）和缺陷（悬挂键）极大地影响了膜的场发射性能。根据以上结果,提出了一种CVD金刚石膜的场发射机制即膜内的缺陷增强膜内的电场,石墨增大电子的隧穿系数以增强CVD金刚石膜的场发射。     

不同反应气源对制备纳米金刚石膜的影响

为确定两种典型的反应气源对制备纳米金刚石膜的影响,分别以CH4/Ar/H2及CH4/N2混合气体作为反应源,用微波等离子体化学气相沉积(MWPCVD)法制备纳米金刚石薄膜.XRD和Raman分析表明两种气源条件下得到的膜材均为金刚石多晶膜,但用CH4/N2气为反应源沉积的膜材中非金刚石相成分明显更多;AFM和SEM对照分析证实所有膜层的平均晶粒尺寸及表面粗糙度均在几十纳米量级,但CH4/N2气源沉积的膜中容易形成异常长大的晶粒,不利于表面质量的提高.研究结果表明,以CH4/Ar/H2混合气体作为反应气源可制备物相组成纯度更高、表面形态更为优越的纳米金刚石膜.     

沉积参数对化学气相沉积纳米金刚石薄膜的影响

用强电流直流伸展电弧化学气相沉积金刚石薄膜装置,在CH4-Ar和CH4-H2-Ar气氛中沉积了纳米金刚石薄膜,研究了沉积气氛中H2加入量和沉积压力对金刚石薄膜显微组织和生长机制的影响.沉积气氛中H2含量对金刚石薄膜的表面形貌、晶粒尺寸和生长速度有显著影响,随着H2含量增加,金刚石晶粒尺寸增大,薄膜生长速度提高.在1%CH4-Ar气氛中沉积的纳米金刚石薄膜,晶粒尺寸细小,薄膜表面形貌光滑平整.在1%CH4-少量H2-Ar气氛中沉积的金刚石薄膜,晶粒尺寸小于100nm,薄膜表面形貌较平整.随着沉积压力提高,金刚石薄膜的生长速度增大.用激光Ram an对金刚石薄膜进行了表征.     

fabrication of diamond membranes for MEMS using reactive ion etching of silicon

Polycrystalline diamond thin film has been grown on a silicon substrate using high pressure microwave plasma-assisted chemical vapor deposition from a gas mixture of methane and hydrogen at a substrate temperature of 950°C. A simple process flow has been developed to fabricate optically transparent polycrystalline synthetic diamond membranes/windows employing reactive ion etching (RIE) of a single crystal silicon substrate using an electron beam evaporated aluminum thin film mask pattern formed by photolithography. Scanning electron microscopy has been used to study the morphology of as-grown diamond thin films.     

基片预处理对MWPCVD金刚石薄膜的影响

利用自行研制的石英钟罩式微波等离子体化学气相沉积金刚石薄膜装置，研究了硅基片的不同预处理方式对沉积结果的影响。通过扫描电子显微镜形貌观察和喇曼谱分析表明，基片预处理能提高形核密度；用于预处理的金刚石研磨膏的粒度不同，影响金刚石薄膜沉积时的形核密度、晶形和薄膜的质量；表面划痕对沉积金刚石薄膜的影响具有双重性。     

两段成长法改善微波电浆辅助化学气相沉积多晶金刚石之品质

以化学气相沉积法成长多晶金刚石薄膜时,薄膜的品质会受到成长时间、成长压力、反应气体比例、偏压与否及成核的机制等因素影响.研究采用微波电浆辅助化学气相沉积(MPECVD)法,以甲烷(CH4)和氢气(H2)作为反应气体原料,在P型(111)硅基板沉积多晶金刚石薄膜.典型沉积多晶金刚石薄膜的制程可分为四个阶段:抛蚀表面阶段、渗碳阶段、偏压增强成核(BEN)阶段及成长阶段.研究将成长阶段划分为两个阶段,第一阶段压力较低(成长Ⅰ阶段),第二阶段压力较高(成长Ⅱ阶段).结果表明:第一阶段可大大改善金刚石薄膜的品质,所获多晶金刚石薄膜的晶粒具有明确的颗粒边界、较低的碳化物或缺陷,电导率急剧降低,显现出本徵金刚石半绝缘的性质.可以认为金刚石薄膜品质的改善完全为低压成长所致.实验发现在成长Ⅰ阶段或成长Ⅱ阶段施加偏压时,只会降低多晶金刚石薄膜的品质.     

微波等离子体化学气相沉积——一种制备金刚石膜的理想方法

综述了微波等离子体化学气相沉积(MPCVD)法制备金刚石膜技术,表明MPCVD是高速、大面积、高质量制备金刚石膜的首选方法。介绍了几种常用的MPCVD装置类型,从MPCVD装置的结构特点可以看到,用该类型装置在生长CVD金刚石膜时显示出独特的优越性和灵活性。用MPCVD法制备出的金刚石膜其性能接近甚至超过天然金刚石,并在多个领域得到广泛应用。     

微波等离子体化学气相沉积金刚石膜装置的研究进展

综述了各种微波等离子体化学气相沉积（MPCVD）金刚石膜装置的结构及工作原理,并对它们各自的优缺点做了比较分析;基于MPCVD金刚石膜装置的发展现状,构想设计了一种新型高效的大功率大面积快速沉积CVD金刚石膜装置,并对其可行性做了初步分析研究。     

Microstructural and electrical studies on diamond films

X-ray diffraction, atomic force microscopy and electrical studies were performed on 2-3 μm thick diamond films on silicon substrates. The films were produced by the microwave plasma chemical vapour deposition method. The films were polycrystalline having a grain size of 32.1 nm. From room temperature current-voltage measurements, it was found that the charge transport mechanism was due to the thermionic emission over the potential barrier of 1.3 eV.     

金刚石厚膜的晶界对耐磨性的影响

用直流辉光等离子体化学气相沉积制备金刚石厚膜,用氢的微波等离子体对其抛光截面进行刻蚀,研究了晶界对金刚石厚膜耐磨性的影响.结果表明：在金刚石膜的生长过程中,随着甲烷流量的增加,金刚石膜的晶界从纵向排列为主过渡到网状结构,晶粒内部缺陷逐渐增加,杂质、空洞主要分布于晶界处．金刚石膜的磨耗比随着晶界密度、宽度、杂质含量及晶粒内部缺陷的增加而下降．晶界是杂质、空洞主要富集区,是影响金刚石厚膜耐磨性的主要因素．     

水冷反应室式MWPCVD制备金刚石膜装置研制

微波等离子体化学气相沉积(MWPCVD)是制备金刚石膜的一种重要方法.为了获得金刚石膜的高速率大面积沉积,研制成功了水冷反应室式MWPCVD制备金刚石膜的装置.装置在微波输入功率为3.0 kW时能长时间稳定运行,并在硅衬底上沉积出金刚石膜.     

氧气对MWPCVD制备金刚石膜的影响

在水冷反应室式微波等离子体化学气相沉积装置中以混合的CH4/H2/O2为反应气体,研究了O2浓度对制备金刚石膜的影响.实验发现,很低浓度的O2会显著促进金刚石的沉积,并稍稍抑制非晶C的沉积,因而沉积膜中非晶C的含量急剧下降;较高浓度的O2会同时抑制金刚石和非晶C的沉积,但由于抑制金刚石的作用更强烈,沉积膜中非晶C的含量反而有所升高.另外,O2的存在,有利于沉积颗粒较小的金刚石膜.     

甲烷浓度对金刚石薄膜质量的影响

纳米金刚石薄膜具有优异的性能,已在多个领域获得广泛应用.但微波等离子体化学气相沉积制备的金刚石薄膜质量却严重受沉积工艺的影响,为了深入了解沉积工艺对制备的金刚石薄膜质量的影响,本文详细研究了甲烷浓度对微波等离子体化学气相沉积( MPCVD)金刚石薄膜质量的影响,利用扫描电镜、X射线衍射、拉曼光谱以及原子力显微镜对其进行...