负衬底偏压热灯丝CVD金刚石膜成核的研究

本文利用扫描电子显微镜和原子力显微镜研究了Si(100)衬底上热灯丝金刚石膜成核过程.在-240V和250mA下,在镜面抛光的Si(100)衬底上金刚石最大成核密度超过了1010cm-2.研究表明,负衬底偏压增强成核主要是发射电子和离子轰击的结果.     

等离子体CVD金刚石薄膜衬底正偏压增强成核效应机理研究

衬底正偏压增强成核效应是最近等离子体ＣＶＤ金刚石薄膜中光滑衬底表面金刚石的成核研究发现的，它对于增强和控制金刚石在非金刚石衬底光滑表面的成核行为具有重要的意义。基于已经得到的实验结果。本文分析了衬底正偏压作用于成核过程的机理，提出了这种效应的电子流密度模型，并且给出了正偏压增强效应与沉积参数的关系，描述了正偏压处于过渡和饱和区时的成核状态，合理地解释了所谓“正偏压阻止成核”现象，本模型的结果与已经     

利用发射电子法经由热灯丝CVD在Si(100)上合成局域异质外延金刚石膜

本文利用发射电子法经由热灯丝CVD在Si(100)上获得了局域异质外延金刚石膜.由Raman背散射强度(在1332cm-1处)旋转角依赖关系表明,金刚石膜与Si(100)的定向关系为dia(100)∥Si(100)和dia[110]∥Si[110].在金刚石膜的成核阶段,位于衬底和灯丝之间的电极相对于灯丝施加一负偏压,获得的金刚石膜用扫描电镜和Raman谱表征.对实验结果进行了简要的讨论.     

化学气相沉积金刚石薄膜成核机理研究

本文综述了在化学气相沉积（Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ,ＣＶＤ）金刚石薄膜过程中非金刚石衬底表面金刚石成核机理研究进展。主要讨论了衬底表面缺陷诱导金刚石成核模型,指出最大原子团的存在决定了金刚石成核是否能够在衬底表面发生;分析了金刚石在非金刚石衬底成核时的过渡层问题,提出了过渡层存在机理;对于在等离子体ＣＶＤ中的偏压增强金刚石成核效应,提出的负偏压离子流增强成核模型和正偏压电     

[100]定向织构生长金刚石薄膜的红外光学性能研究

采用微波等离子增强化学气相沉积法在(100)镜面抛光的硅片衬底上实现了金刚石薄片[100]定向织构生长.并用扫描电子显微镜、拉曼散射和傅立叶红外光谱仪分析测试了不同工艺得到的金刚石薄片的表面形貌、组成结构和红外性能.结果表明:负偏压辅助定向成核和氢的等离子刻蚀不仅促进了金刚石薄膜的定向织构生长,而且还能刻蚀成核期的非金刚石成分.从而提高了金刚石薄片的红外光透过特性.     

C60膜上金刚石的成核与生长形貌研究

本文研究了HFCVD系统中覆盖有C60膜的Si(100)衬底上金刚石的成核与形貌特征.结果表明,C60能大幅度提高金刚石成核密度;C60氢化预处理能大幅度促进金刚石成核,但要合理控制CH4的浓度和预处理时间;随衬底温度的升高,金刚石晶粒由球状变为菜花状聚晶.     

不同衬底材料上金刚石薄膜成核特点的研究

研究了金刚石薄膜在WC-6;Co硬质合金、金属W和单晶Si片上的成核特点.实验结果表明,金刚石薄膜在上述衬底材料上的成核特点和成核机制不同.用于衬底研磨预处理的金刚石微粉粒度对金刚石在单晶Si片上的成核密度有较大影响,而对在WC-6;Co硬质合金和金属W上的成核密度没有太大影响.     

辉光放电对负偏压增强热丝化学气相沉积碳纳米管的准直生长作用研究

利用负偏压增强热丝化学气相沉积在不同的负偏压和压强下,在沉积有不同厚度NiFe膜的Si衬底上制备了碳纳米管,并用扫描电子显微镜研究了它们的生长.发现在无辉光放电的情况下,碳纳米管弯曲生长,而在辉光放电时,碳纳米管准直生长,表明辉光放电对碳纳米管的准直生长起到了重要的作用.由于辉光放电的产生,在衬底表面附近形成很强的电场.相对无辉光放电时的电场,场强提高了两个数量级.本工作详细地研究了辉光放电对碳纳米管的准直生长作用.     

金刚石膜在Si(100)衬底上的选择沉积

采用自行设计的微波等离子体化学气相沉积系统,利用铜网作为模板实现了在Si(100)衬底上金刚石膜的选择沉积.用场发射扫描电子显微镜(SEM)、Raman散射谱对样品进行了表征与分析.并与同样生长条件下未采用模板时得到的金刚石样品进行了比较.结果发现,采用模板后,金刚石膜的成核密度和质量都得到很大提高.     

大尺寸单晶金刚石薄膜的外延生长

用电子回旋共振等离子体增强的化学汽相沉积法, 在单晶硅衬底上外延生长出了近于100μm2的单晶金刚石薄膜.使用的原料气体是高纯的氢气和甲烷,生长前没有对衬底做划痕和研磨等预处理.生长中是把衬底放在ECR共振区,并施加了射频负偏压.研究证实,在单晶金刚石薄膜的外延中,硅衬底表面形成高质量结晶的β-SiC过渡层是外延生长金刚石单晶的关键条件;而射频负偏压对于β-SiC过渡层的形成是致关重要的条件.     

High quality nanocrystalline silicon thin film fabricated by inductively coupled plasma chemical vapor deposition at 350 °C

High quality nanocrystalline silicon (nc-Si) film was deposited by inductively coupled plasma chemical vapor deposition (ICP-CVD) without substrate RF bias at 350 °C. The nc-Si with a dense crystalline structure of the columnar type grew from the bottom to the top of the nc-Si film. A troublesome incubation layer did not exist at the bottom of the fabricated nc-Si film. A grain size of 40 nm was measured by using a SEM image. When a RF bias of 100 and 200 W was applied to the substrate to induce ion bombardment on the substrate, the crystalline structure and grains were not observed and a-Si deposition became dominant. The transition from nc-Si deposition into a-Si deposition can be attributed to ion bombardment which prevents nucleation and crystal growth at the surface of deposition. This shows that the reduction of ion bombardment can be a key factor to fabricate high quality nc-Si film. By using ICP-CVD with no substrate RF bias, ion bombardment can be reduced, while the density of plasma is kept high, so that high quality nc-Si can be fabricated due to the enhancement of crystalline growth on the surface.     

金刚石薄膜在硬质合金基体上的生长及附着强度研究

硬质合金是制作金刚石薄膜涂层刀具的重要基体材料,金刚石薄膜在硬质合金基体上的成核、生长及界面特征直接影响其附着强度.本文通过扫描电镜、X射线衍射分析、X射线光电子谱(XPS)及断续切削实验,研究了硬质合金基体含Co量对金刚石薄膜成核、生长及附着强度的影响.研究结果表明,经酸洗处理后,硬质合金基体含Co量对金刚石薄膜成核、生长没有太大影响.但对其附着强度有很大影响.含Co量越高,附着强度越低.酸腐蚀去Co处理后基体表面变得疏松、不连续非金刚石碳界面的存在及热膨胀系数较大是含Co量较高时,附着强度下降的主要原因.     

Systematic study of various stages during the growth process of diamond-like carbon film by atomic force microscopy

The diamond like carbon (DLC) films have been grown by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD) in methane-argon plasma. In PECVD, the plasma sheath potential drop arising due to argon plasma was utilized to grow the DLC film on silicon (100) substrate at low temperature without using any external negative bias voltage. The growth process of the DLC film has been studied completely starting from nucleation to continuous film by atomic force microscopy. It was seen that the DLC film nucleates around surface defects on the substrate and that the film growth occurs by both adatom deposition and coalescence between nucleated islands. Raman spectrum confirms that the DLC film nucleates excessively in sp² hybridized state and that during the growth process the fraction of sp³ CH_x (x = 1 − 3) increases which leads to the amorphous nature of the film. Long range uniformity of the film was identified using scanning electron microscope.     

Investigation of Pretreated Silicon Wafers for CVD Growth of Diamond Film

Difference between lattice constants of silicon (Si) and diamond is approximately 52%. Therefore Si_1—xC_x which has a lattice constant between two materials should be formed on Si substrate to be diamond nucleation sites and reduce the stress between the diamond film and Si substrate. Si wafers with carbonization and dc-biasing pretreatment were prepared in a microwave plasma chemical vapor deposition (CVD) system, then they were investigated by Raman spectroscopy, Photoluminescence (PL), chemical etching and scanning electron microscope (SEM) to study the pretreatment effect. This was achieved by studying a series of samples pretreated by carbonization and dc-biasing.     

Remote plasma deposition of microcrystalline silicon thin-films: Film structure and the role of atomic hydrogen

Microcrystalline silicon films grown in an expanding thermal plasma, i.e. in the absence of ion bombardment, are found to be porous and rich in nano-sized voids. By carrying out an extensive investigation on the material quality of films deposited in the amorphous-to-microcrystalline transition regime, on the microcrystalline silicon growth development, and on the influence of the substrate temperature, it is concluded that the inferior material quality is related to the lack of a sufficient amount of amorphous silicon tissue. As possible cause for the insufficient amount of amorphous silicon tissue, the interaction of atomic hydrogen with amorphous silicon films has been studied in order to highlight a possible competition between film growth and H-induced etching of amorphous silicon, and between film growth and H-induced surface/film modification. The etch rates obtained are too low to compete with film growth. Furthermore, atomic H cannot be considered responsible for the poor quality of amorphous tissue present in the microcrystalline silicon films, as the H up-take mainly takes place in divacancies. These results suggest that ion bombardment may be a necessary condition to provide good quality microcrystalline silicon films.     

离子轰击对准直碳纳米管生长的影响

利用负偏压增强热丝化学气相沉积系统,在辉光放电的情况下制备出准直碳纳米管,并用扫描电子显微镜研究了不同负偏压对准直碳纳米管生长的影响.结果表明随着负偏压的增大,准直碳纳米管的平均直径减小,平均长度增大.由于辉光放电的产生,在衬底表面附近形成阴极鞘层,以及在阴极鞘层内形成大量的离子和在衬底表面附近形成很强的电场导致了离子对衬底表面的强烈轰击.最后,分析和讨论了离子的轰击对准直碳纳米管生长的影响.     

Diamond nanorods from nanocrystalline diamond films

Diamond nanorods (DNRs) have been prepared by hydrogen plasma post-treatment of nanocrystalline diamond films in radio-frequency (RF) plasma-assisted hot-filament chemical vapor deposition. Single-crystal diamond nanorods with diameters of 3–5 nm and with lengths up to 200 nm grow under hydrogen plasma irradiation of nanocrystalline diamond thin film on the Si substrate at high temperatures. The DNRs growth occurs from graphite clusters. The graphite clusters arises from the etching of diamond carbon atoms and from the non-diamond phase present in the parent film. The graphite clusters recrystallized to form nanocrystalline diamonds which further grow for diamond nanorods. The negative applied bias and surface stresses are suggested to support one-dimensional growth. The growth direction of diamond nanorods is perpendicular to the (1 1 1) crystallographic planes of diamond. The studies address the structure and growth mechanism of diamond nanorods.     

在预涂陶瓷过渡层的多谱段ZnS衬底上沉积金刚石膜的探索研究

本文采用真空电子束蒸镀技术在多谱段ZnS衬底上沉积了适合金刚石膜沉积的致密陶瓷过渡层,并利用微波等离子体CVD金刚石膜低温沉积技术进行了金刚石膜沉积研究.发现在陶瓷过渡层上的金刚石形核极其困难,其原因可能是陶瓷涂层在沉积过程中龟裂导致ZnS蒸汽扩散逸出干扰金刚石形核所致.本文采用诱导形核技术在过渡层/ZnS试样表面观察到极高密度(1010/cm2)的金刚石形核,并对金刚石/过渡层/ZnS试样的红外透过特性进行了评价.