【作者】 王国菊；

【导师】 严辉；

【作者基本信息】 北京工业大学 ， 材料物理与化学， 2004， 硕士

【摘要】 在本研究工作中，用热丝化学气相沉积（HFCVD 或 Cat-CVD）方法，在温度为 300oC-500oC 的单晶 Si(100)衬底上，以 CH4、SiH4和 H2为反应气体制备了β-SiC 薄膜，研究了流量、偏压、衬底温度等沉积参量对β-SiC 薄膜结构、成分和生长速率的影响。实验发现，β-SiC 薄膜的结构和生长速率受 SiH4流量的影响较大，而受 CH4流量的影响较小。适当的负偏压和较高的正偏压都能提高薄膜的结晶程度，使晶粒尺寸增加，而过高的负偏压则对薄膜表面造成过度轰击，抑制晶粒长大。在沉积过程中加入适量的 CF4，首次发现 CF4能有效刻蚀 SiC 薄膜中的 O 杂质和非晶相的 SiC，提高β-SiC 薄膜的结晶程度。 用等离子体化学气相沉积（PECVD）方法，在温度为 500oC-700oC 的单晶Si(100)衬底上，在 100-200W 的射频功率下，分别以 CH4+SiH4+H2 和 CF4+SiH4+H2为反应气体，沉积了β-SiC 薄膜。测量结果表明，以 CF4为 C 源制备的β-SiC 薄膜的 Si-C 的有序度优于相同条件下以 CH4为 C 源制备的β-SiC 薄膜的 Si-C 的有序度。 对β-SiC 薄膜的场发射特性进行了研究。测量了不同结构的β-SiC 的场发射性能，测量结果表明纳米β-SiC 薄膜相对于非晶 SiC 薄膜的场电子发射性能有明显的提高，并且减小晶粒尺寸有利于提高纳米β-SiC 薄膜的场发射性能，着重分析了晶粒尺寸对场发射性能的影响机制。 用 HFCVD 法实现了准直碳纳米管的定向生长，用溶液理论和等离子体理论分析了 N2和等离子体在碳纳米管定向生长中的作用，并分析了在含 N 的气氛中竹节状碳纳米管形成的原因。更多还原

【Abstract】 In this study, β-SiC films were prepared on Si (100) substrate by Hot FilamentChemical Vapor Deposition (HFCVD or Cat-CVD) at substrate temperature of300-500oC using CH4, SiH4 and H2. The effects of deposition parameters on thestructure, composition and growth rate of β-SiC films are studied. Experimentresults indicate that the crystallinity and growth rate of β-SiC films are mainlyinfluenced by SiH4 fluxes while slightly by CH4. Appropriate negative and positivebias all can improve the crystallinity of β-SiC films, and the crystal size can beincreased accordingly, whereas too high negative bias can limit the β-SiC crystalsgrowth due to the strong bombardment of ions. For the first time, it is found that theoxygen contamination and amorphous SiC in the β-SiC films can be reduced byaddition of CF4 into precursor gases of CH4+SiH4+H2, thus the crystallinity of β-SiCfilms can be improved evidently. Using precursor gases of CH4+SiH4+H2 and CF4+SiH4+H2, β-SiC films wereprepared by Plasma Enhanced Chemical Vapor Deposition (PECVD) at temperatureof 500-700oC under RF-power of 100-200W. Measurement results indicate that theorder degree of the Si-C bonds prepared using CF4+SiH4+H2 is superior to that ofprepared using CH4+SiH4+H2 under the same experiment conditions. Electrical characteristics of β-SiC films were studied. The measurement resultsof field emission characteristics of β-SiC films indicate that the field emissioncharacteristics of nanocrystalline β-SiC films is superior to that of amorphous SiCfilms, and the field emission characteristics can be improved by decreasing the β-SiCcrystal size. The effects of crystal size on field emission characteristics areanalyzed. Aligned carbon nanotubes (ACNTs) were synthesized by HFCVD in N2 andglow discharge environment. The effects of N2 and glow discharge on the growth ofACNTs are analyzed based on the solution and plasma theory, and the formationmechanism of bamboo like CNTs synthesized in N2 environment is discussed.更多还原