微波等离子刻蚀CVD金刚石膜提高机械研磨效率

针对低温低压化学气相沉积(CVD)金刚石膜表面粗糙且厚薄不均,普通的方法抛光金刚石膜效率低的现象,采用空气等离子刻蚀金刚石膜与机械研磨相结合的抛光工艺,提高了金刚石膜的抛光加工效率.并与纯机械研磨法比较,通过观察样品的表面形貌,说明等离子刻蚀的作用.     

倒挂井法修建防渗墙设计

倒挂井是由在坝轴线上若干个拱圆井组成,自上而下开挖、浇筑井壁,自下而上回填黏土或混凝土而形成连接的防渗墙的一种方法,这种方法不需要大型设备和专业队伍,易于推行。     

Growth of Aligned Carbon Nanotubes through Microwave Plasma Chemical Vapor Deposition

Aligned carbon nanotubes (CNTs) were synthesized on glass by microwave plasma chemical vapor deposition (MWPCVD) with a mixture of methane and hydrogen gases at the low temperature of 550~C. The experimental results show that both the self-bias potential and the density of the catalyst particles are responsible for the alignment of CNTs. When the catalyst particle density is high enough, strong interactions among the CNTs can inhibit CNTs from growing randomly and result in parallel alignment.     

射频等离子体制备类金刚石薄膜及其表征

采用射频等离子体技术,以CH4和H2为反应气体,在单晶硅片和载玻玻璃片上成功制备出了高质量的类金刚石薄膜.采用扫描电镜、原子力显微镜、Raman光谱、红外光谱、显微硬度计表征了类金刚石薄膜的表面形貌、微观结构、光学性能和复合硬度.结果表明,制备出的类金刚石薄膜表面十分平整光滑,表面粗糙度极低,平均粗糙度Ra为0.492 nm;薄膜中含有sp2,sp3杂化键,具有典型的类金刚石结构特征;光学透过率比较高,薄膜的复合硬度可以高达507.3 kgf/cm2.     

CVD金刚石薄膜半导体材料的研究进展

含Ⅲ族与Ⅴ族元素掺杂的金刚石是宽禁带的半导体材料,同时具有优异的物理和化学特性,在电子器件与光电子器件方面的应用具有极大潜力,成为近几年来国内外研究的热点之一。介绍了目前常用的掺杂方法、技术水平及金刚石半导体的应用前景。     

Deposition and Boron Doping of Nano-Crystalline Diamond Thin Films on Poly-Crystalline Diamond Thick Films

Boron-doped nano-crystalline diamond (NCD) thin films have been successfully de-posited on well-polished poly-crystalline diamond (PCD) thick films in a microwave plasma en-hanced chemical vapor deposition (MPCVD) reactor for the first time.Different surface pretreat-ment techniques are carried out under different gas conditions (CH4,H2,Ar,and CH4 /H2) to eliminate the effect of grain boundaries on the growth of a smooth NCD intrinsic layer.Well doped NCD films have been fabricated in CH4/H2/B2H6 plasma by varying the atomic ratio of B/C and the substrate temperature.Atomic force microscopy (AFM) results show that pretreat-ment in pure CH4 plasma at 1000C is most effective for NCD growth,while hydrogen containing plasma is harmful to the surface smoothness of NCD thin films.Doping research indicates that the optimum parameters for the boron-doping of high-quality NCD thin films are B/C=300ppm (10-6) and 800C.     

Synthesis of a Large Diamond Crystal with a Smooth （100） Facet at its Top Through MPCVD

A large diamond crystal up to 500μm in diameter with a smooth(100)facet at its top has been synthesized on Mo substrate through microwave plasma chemical vapor deposition(MPCVD).Its morphology and quality were characterized by scanning electron microscopy(SEM),and the growth mechanism was roughly illustrated from both macroscopic and microscopic viewpoints.It was found that morphological instabilities are a major factor resulting in synthesis of large diamond crystals,moreover,high microwave power density(MPD),high CH4 concentrations,high pressure,high substrate surface temperature and the addition of a small amount of O2 were also necessary for the synthesis of large diamond crystals.     

衬底对CVD生长石墨烯的影响研究

石墨烯有独特的结构和优异的性能,在电子、信息、能源、材料和生物医药等领域都有着广阔的应用前景。为了更好的应用这种新型材料,如何大规模可控合成高质量石墨烯是一个必须克服的困难。相比与机械剥离法、化学氧化还原法和碳化硅表面外延生长法,化学气相沉积法（CVD）因其可以生长大面积高质量连续石墨烯膜而倍受关注。基于石墨烯的生长机理,从衬底材料的角度,综述了近几年衬底对CVD生长石墨烯的影响的研究进展。展望了衬底选择的发展新趋势。     

金刚石半导体研究进展

金刚石具有一系列优异的物理化学性能,特别是独特的电学和热学性能,使其在半导体领域具有极佳的应用前景.通过详细评述金刚石的各种性能,以及与其他半导体材料的性能比较,提出了金刚石在半导体器件应用领域的优势.详细介绍了金刚石半导体掺杂以及金刚石半导体器件的种类和应用,并在此基础上展望了金刚石在半导体领域的应用.     

衬底位置对制备（100）面金刚石薄膜的影响

本文利用5kW微波等离子体装置,在直径22mm的石英上沉积金刚石薄膜。实验研究了衬底在不同位置对沉积金刚石薄膜的质量产生的影响。实验中将2块石英衬底编号为A和B,样品A被放在偏离钼基片台中心5mm的位置,使石英的中间区域偏离等离子体球,而边缘区域处于等离子体球的下方。通过SEM和拉曼光谱表征所沉积的金刚石膜,对比样品A的中间和边缘区域发现中间的区域金刚石膜的质量差且不均匀,边缘区域则长出取向一致的（100）面金刚石。通过分析认为,较高的温度、大的等离子体密、合适的碳源浓度度等条件有利于（100）面金刚石薄膜的沉积。随后改进工艺,将样品B放在基片台中心使其处于等离子体的正下方,并调整生长温度和甲烷浓度,成功的获得了高质量均匀的（100）面金刚石薄膜。