C-H体系CVD金刚石薄膜

化学气相淀积金刚石薄膜过程中,ＣＨ３和Ｃ２Ｈ２是金刚石生长的主要前驱基团。Ｃ２Ｈ２与ＣＨ３浓度比（［Ｃ２Ｈ２］／［ＣＨ３］）的变化将影响金刚石薄膜的生长取向。用非平衡热力学耦合模型设计了Ｃ－Ｈ体系ＣＶＤ金刚石薄膜生长过程中Ｃ２Ｈ２浓度和ＣＨ３浓度随淀积条件的变化,并进一步获得了［Ｃ２Ｈ２］／［ＣＨ３］随衬底温度和ＣＨ４浓度的变化关系,从理论上探讨了金刚石薄膜（１１１）面和（１００）面取向生长与淀积     

激光注入功率对激光辅助化学气相沉积金刚石薄膜的影响

对激光注入功率对激光辅助化学气相沉积金刚石薄膜的影响进行了数值模拟计算和实验研究. 应用二维气相输运模型和包括34个基元反应的化学动力学模型,对LACVD化学气相动力学进行了数值模拟研究;结果表明激光平均注入功率对衬底表面的CH3、H的浓度有影响,而对衬底表面的H2、C2H3的浓度则无影响.本文应用层堆积模型,以CH3作为SP3(金刚石)相生长的前驱物,而C2H3作为SP2(石墨)相生长的前驱物,其中SP3相的相对含量标志金刚石薄膜的质量,模拟计算研究了激光平均注入功率对金刚石薄膜生长速度和生长质量的影响. 实验利用XeCl(308 nm)准分子激光器作为碳源气体的解离光源,激光器单脉冲能量200 mJ,脉冲重复率2～8 Hz;丙酮为碳源气体;H2为辅助气体,通过2000°C的灯丝预先解离;(CH3)2CO/H2为0.4%;P型硅为衬底,温度870°C;生长出高质量金刚石薄膜;实验结果表明平均注入激光功率对金刚石薄膜的生长速度和质量有重要影响.理论计算结果与实验结果吻合.(OE11)     

脉冲ArF准分子激光淀积SiC/Si(100)薄膜的最佳晶化温度及光致发光

用脉冲 Ar F准分子激光熔蚀 Si C陶瓷靶 ,在 80 0℃ Si(10 0 )衬底上淀积 Si C薄膜 ,经不同温度真空 (10 - 3Pa)退火后 ,用 FTIR、XRD、TEM、XPS、PL 谱等分析方法 ,研究了薄膜最佳晶化温度及表面形态、结构、组成 ,并对在最佳退火温度处理后的样品进行了化学态、微结构及光致发光的研究 .结果表明 ,在 Si(10 0 )上 80 0℃淀积的样品为非晶Si C薄膜 .经 85 0— 10 5 0℃不同温度真空退火后 ,Si C薄膜经非晶核化 -长大过程 ,在 980℃完成最佳晶化 .随退火温度的变化 ,薄膜中可能存在 3C- Si C与 6 H- Si C的竞争生长或 /和 3C- Si C相的长、消 (最佳温度     

等离子增强化学汽相淀积a-SiC:H簿膜的AES研究

用俄歇电子能谱(AES)对等离子增强化学汽相淀积(PECVD)氢化非晶碳化硅(a-SiC∶H)薄膜进行了组分的深度剖析、半定量分析以及化学分析.俄歇深度剖析曲线表明PECVD淀积的薄膜均匀性非常好;用俄歇半定量结果比较了薄膜成分同淀积工艺参量之间的一些关系;根据实验获得的Si LVV和CKLL俄歇谱比较和讨论了不同[Si]/[C]浓度比薄膜的化学特征.     

准分子激光低温淀积金刚石薄膜

金刚石薄膜以其优异的力、热、电、声、光等性质而具有广泛的应用前景。近年来，一系列化学气相淀积（CVD）技术被用于金刚石薄膜的合成，并取得了一系列的进展．但目前多数CVD方法中基片温度较高（大于800℃），这极大地限制了金刚石薄膜在光学、半导体和光电子学等方面的应用．因此，低温生长高质量的金刚石薄膜已成为目前重要的研究课题．本工作在EACVD基础上，辅以准分子激光（XeCl308nm）溅射C靶产生激光等离子体，在较低温度（500～600℃）下生长了高质量的晶态金刚石薄膜．工作气体为CH4／H2，浓度比为0．7％～1％；热灯丝温…     

Si上Si_(1-x-y)Ge_xC_y三元合金薄膜的生长

研究了 Si衬底上 Si Ge C合金薄膜的生长。以 C2 H4 为 C源、采用快速加热超低压化学气相淀积 (RTP/VL P- CVD)的非平衡生长技术 ,在 Si(10 0 )衬底上生长出具有一定代位式 C含量的硅基 Si Ge C合金。实验表明 :较低的生长温度和较高的 Si H4 /C2 H4 流量比有利于代位式 C原子的形成和材料晶体质量的提高。     

Si1-x Gex:C缓冲层的生长温度对Ge薄膜外延生长的影响

用化学气相淀积方法,在Si(100)衬底上生长Si1-x Gex:C合金作为缓冲层、继而外延生长了Ge晶体薄膜,用X射线衍射(XRD)、俄歇电子能谱(AES)、拉曼(Raman)衍射光谱等对所得到的样品进行了表征测量,着重研究了Si1-x Gex:C缓冲层生长温度对样品结构特征的影响.结果表明:Si1-x Gex:C缓冲层中的Ge原子浓度沿表面至衬底方向逐渐降低,其平均组分随着生长温度的升高而降低.这与较高生长温度(760～820℃)所导致的原子扩散效应相关;在Si1-x Gex:C缓冲层上外延生长的Ge薄膜具有单一的晶体取向,薄膜的晶体质量随着温度的升高而降低.     

CeO_2高K栅介质薄膜的制备工艺及其电学性质

研究了 Ce O2 作为高 K (高介电常数 )栅介质薄膜的制备工艺 ,深入分析了衬底温度、淀积速率、氧分压等工艺条件和利用 N离子轰击氮化 Si衬底表面工艺对 Ce O2 薄膜的生长及其与 Si界面结构特征的影响 ,利用脉冲激光淀积方法在 Si(10 0 )衬底生长了具有 (10 0 )和 (111)取向的 Ce O2 外延薄膜 ;研究了 N离子轰击氮化 Si衬底表面处理工艺对 Pt/ Ce O2 / Si结构电学性质的影响 .研究结果显示 ,利用 N离子轰击氮化 Si表面 /界面工艺不仅影响 Ce O2 薄膜的生长结构 ,还可以改善 Ce O2 与 Si界面的电学性质     

表面粗化高空穴浓度InGaN:Mg性能及其发光二极管应用

利用金属有机物化学气相淀积(MOCVD)技术在蓝宝石衬底上生长了InGaN:Mg薄膜,对不同源流量InGaN:Mg材料特件进行了研究.光学和电学特性观测表明,当外延生长温度在760℃,三甲基铟(TMIn)摩尔流量不变时,随CP2Mg和Ⅲ族源摩尔比([CP2Mg]/[Ⅲ])增加,当In摩尔成分增加,空穴浓度也线性增加;当...     

循环刻蚀工艺对金刚石膜形貌和电阻率的影响

为了制备新型金刚石薄膜辐射剂量计,针对目前金刚石薄膜质量较差,难于满足辐射剂量计要求的问题,采用微波等离子体CVD法,研究了循环刻蚀生长阶段工艺参数(甲烷浓度,基片温度)和刻蚀方法对薄膜形貌、电阻率的影响。结果表明,循环刻蚀生长有利于提高金刚石薄膜的纯度和取向性。当?(甲烷)为0.34%,基片温度为960℃时,可获得[100]晶面取向的、电阻率达1011Ω·cm的金刚石膜,和采用常规工艺所得金刚石薄膜相比,其电阻率提高了3个数量级。     

Molecular view of diamond CVD growth

In this paper, we discuss the simulation of the chemical vapor deposition (CVD) of diamond films on the molecular scale. These simulations are performed using a kinetic Monte Carlo method that combines the surface chemistry that is important to diamond growth with an atomic-scale picture of the diamond surface and its evolving atomic structure and morphology. We address the determination of surface reaction kinetics and growth conditions from experiments and reactor-scale models, and the prediction of polycrystalline film texture and morphology from the molecular-scale results. The growth rates and the concentrations of incorporated point defects as a function of substrate temperature for {100}- and {111}-oriented diamond films are obtained from the molecular-scale growth simulations. The {100} growth rates increase with temperature up to 1200K and then decrease above this value. The {111} growth rates increase with temperature at all of the temperatures studied. The concentrations of point defects in the {100} and {111} films are low at substrate temperatures below 1200K, but increase substantially at higher temperatures. The growth efficiency, measured as the ratio of film growth rate to defect concentration, is maximum between 1100–1200K for both film orientations, suggesting that this temperature range is ideal for CVD diamond growth under the simulated growth conditions.     

SAW器件用金刚石膜的制备工艺研究

针对声表面波( SAW)器件对金刚石膜的要求,采用石英钟罩式微波等离子体化学气相沉积(MPCVD)装置,研究了不同气体体系对金刚石膜生长速率、电阻率、表面形貌、表层C化合态及相对含量(粒子数分数Xc)的影响.结果表明:在H2-CH3COCH3、CH4-H2-Ar和CH4-H2-N2三种气体体系下,金刚石膜的生长速率分别...     

金刚石/硅复合膜的导热特性研究

用金刚石粉,用不同时间在两片镜面抛光的(111)硅基片上分别打磨.两片硅基片打磨后都仍保持镜面特征.采用微波等离子体化学气相沉积系统,利用氢气、甲烷和氧气为前驱气体,在同样参数条件下,在基片上制备了直径5 cm的金刚石薄膜.用扫描电镜和X射线衍射分析两片薄膜结构.分析结果表明其表面形貌基本相同都为(111)择优取向的金刚石薄膜;但X射线衍射分析表明打磨时间较长的薄膜中含有一定量在非晶成分.用热导测试仪测试两薄膜和硅基片的热导率约为:241.7 W/mK,192.9 W/mK和169.3 W/mK.结合扫描电镜和X射线衍射分析结果我们讨论了基底处理对金刚石/硅复合膜的导热特性的影响.     

Growth of diamond films on si(100) with and without boron nitride buffer layer

Diamond films were grown on Si(100) and boron nitride deposited Si(100) substrates using hot filament chemical vapor deposition (HFCVD) technique. Microstructure and morphology of diamond films have been investigated systematically as a function of CH₄ and H₂ ratio and the ambient pressure. The deposited films were characterized by employing techniques such as scanning electron microscopy (SEM) and laser Raman spectroscopy. The average size and growth rate of diamond particles were found to increase with the CH₄ to H₂ ratio and decrease with the ambient pressure. Maximum growth rate of synthetic diamond deposited on Si(100) was found to be ∼3.5 µm/hr for the film deposited at 20 Torr with CH₄:H₂ ∼ 1.5:100 (substrate temperature ∼850°C). In most of these depositions, the morphology of the diamond crystals was cubic with significant secondary nucleation at higher methane concentrations and ambient pressure. The diamond film deposited on Si(100) with BN buffer layer shows an improvement in growth rate and the coverage, and the secondary nucleation was found to be substantially reduced, resulting in relatively smooth morphology. MicroRaman investigations show less amorphous graphite formation and better structural quality of diamond film than the one deposited without the BN buffer layer. On leave from Department of Physics University of Poona, Pune-411007 INDIA     

用PECVD法沉积α-C:H薄膜的研究

本文报导了使用PECVD方法沉积的α-C:H溥膜的工艺条件、薄膜结构和物性之间的联系。指出,α-C:H膜中石墨和金刚石成分的比值密切相关于反应气氛CH_4/(CH_4+H_2)的比例以及沉积系统中的衬底温度和施加在平行板电极之间的直流偏压。最后,利用化学反应平衡方程讨论了α-C:H膜的沉积机理以及[H]基对生成膜结构的影响。     

热丝化学气相沉积法在CH4／H2混合气体中低温生长超薄纳米金刚石膜

用热丝化学气相沉积方法研究了低温(~550℃)和低反应气压(~7 Torr)下硅片上金刚石膜的成核和生长.成核过程中采用2.5%的CH4浓度,在经充分超声波预处理的硅片上获得了高达1.5×1011cm-2的成核密度.随CH4浓度的增加所成膜中的金刚石晶粒尺寸由亚微米转变到纳米级.成功合成了表面粗糙度小于4nm、超薄(厚度小于500nm)和晶粒尺寸小于50nm的纳米金刚石膜.膜与衬底结合牢固.膜从可见光至红外的光吸收系数小于2×104cm-1.用我们常规的HFCVD技术,在低温度和低压下可以生长出表面光滑超薄的纳米金刚石膜.     

金刚石基底上制备(002)AlN薄膜的研究

首先采用微波等离子体化学气相沉积(MPCVD)方法,在O2/H2/CH4混合气体气氛下利用大功率微波在(100)Si片上生长出了异质外延金刚石膜,X-射线衍射(XRD)、拉曼光谱和场发射扫描电子显微镜(FESEM)对薄膜的表征分析结果表明,制备的金刚石膜具有很高的金刚石相纯度,且晶粒排列紧密;继而采用射频磁控反应溅射法,在抛光的金刚石基底上成功制备了高C轴择优取向的氮化铝(AlN)薄膜,研究了不同的溅射气压、靶基距对AlN薄膜制备的影响,XRD检测结果表明,溅射气压低,靶基距短,有利于AlN(002)面择优取向,相反则更有利于AlN薄膜的(103)面和(102)面择优取向;研究了AlN薄膜在以N终止的金刚石基底和纯净金刚石基底两种表面状态上的生长机制,结果发现,以N终止的金刚石基底非常有利于AlN(002)面择优取向生长;从Al-N化学键的形成以及溅射粒子平均自由程的角度,探讨了其对AlN薄膜择优取向的影响。     

纳米金刚石薄膜的制背

采用微波等离子体化学气相沉积系统,利用氢气、甲烷、氩气和氧气为前驱气体,在直径为5 cm的(111)取向镜面抛光硅衬底上沉积出高平整度纳米金刚石薄膜.利用扫描电镜、X射线衍射谱和共焦显微显微拉曼光谱我们分析了薄膜的表面形貌和结构特征.该薄膜平均粒径约为20 nm.X射线衍射谱分析表明该薄膜具有立方相对称 (111)择优取向金刚石结构.在该薄膜一阶微显微拉曼光谱中,1 332 cm-1附近微晶金刚石的一阶特征拉曼峰减弱消失,可明显观测到的三个拉曼散射峰分别位于1 147 cm-1、1 364 cm-1和1 538 cm-1,与己报导的纳米金刚石拉曼光谱类似.该方法可制备出粒径约为20 nm粒度分布均匀致密具有较高含量的sp3键的纳米金刚石薄膜.     

Effects of deposition pressure on the microstructural and optoelectrical properties of B-doped hydrogenated nanocrystalline silicon (nc-Si:H) thin films grown by hot-wire chemical vapor deposition

We report on the effects of deposition pressure P_d on the growth and properties of the B-doped nanocrystalline silicon (nc-Si:H) thin films grown by hot-wire chemical vapor deposition (HWCVD) at very high hydrogen dilution of 98.8%. We found that the crystallinity of nc-Si:H or μc-Si:H films is not only determined by hydrogen dilution but also the concentration ratio of atomic H to SiH₃ ([H]/[SiH₃]) on the growing surface which is varied with deposition pressure P_d. Furthermore, there is a threshold of [H]/[SiH₃] ratio which we name as overfull hydrogen (OH). When the [H]/[SiH₃] ratio is lower than the threshold OH ([H]/[SiH₃]<OH), the crystallinity of the nc-Si:H or μc-Si:H films increases with increasing [H]/[SiH₃] ratio. But when the [H]/[SiH₃] ratio is higher than the threshold OH ([H]/[SiH₃]>OH), the crystallinity decreases with increasing [H]/[SiH₃] ratio. Finally, the high conductivity of 4.22 S cm⁻¹ of the B-doped nc-Si:H thin film deposited at 15 Pa is obtained.     

Microtexture and Grain Boundaries in Freestanding CVD Diamond Films: Growth and Twinning Mechanisms

Three groups of free‐standing chemical vapor deposition (CVD) diamond films formed with variations in substrate temperature, methane concentration, and film thickness are analyzed using high‐resolution electron back‐scattering diffraction. Primarily {001}, {110}, and {111} fiber textures are observed. In addition, corresponding primary and higher order twinning components are found. As interfaces, high angle, low angle, primary twin, and secondary twin boundaries are observed. A growth and a twinning model are proposed based on the sp³ hybridization of the bond in the CH₄ molecule that is used as the deposition medium.