外延生长半导体材料中的微缺陷对其性能及应用有着关键性的影响,为此微观缺陷的研究的必要性就显得更突出了。而透射电子显微学恰是进行微缺陷研究的重要手段。本工作就Si衬底上外延生长Ga As开展研究。实验样品有两类:(1)在Si衬底上直接生长Ga As;(2)在Si衬底上先生长一定量的Ga AsIn Ga As超晶格作为缓冲层,而后再生长Ga As。实验结果表明两类样品中的Si衬底晶体完整度很好,外延层中存在着大量的晶体缺陷,但缺陷性质不完全类同。对于第(1)类样品缺陷以位错为主,同时有一些微孪 Microdefects in epitaxial growth of semiconductor materials have a crucial impact on their performance and application, and the need for the study of microscopic defects becomes more prominent. Transmission electron microscopy is just an important method for microdefects. In this work, GaAs was epitaxially grown on Si substrate. There are two types of experimental samples: (1) Ga As is directly grown on Si substrate; (2) a certain amount of Ga AsIn GaAs superlattice is grown as a buffer layer on Si substrate and then GaAs is grown. The experimental results show that the crystal integrity of the Si substrate in the two samples is very good, and there are a lot of crystal defects in the epitaxial layer, but the defect properties are not exactly the same. For the (1) sample defects are dislocations dominated, with some micro-twists