生长在Si上的GaAs外延膜中有关深能级缺陷与其形貌间的关联研究

由于在GaAs和Si单晶材料间有着很大的格子常数及线性热膨胀系数差别，所以在St上生长的GaAs异质外延薄膜（GaAs／Si）中会存在着界面失配形变与高密度的结构缺陷。我们的实验显示，GaAs／Si外延膜的无序与其生长条件有关，尤其与其［As］／［Ga］比密切相关。与GaAs／Si无序相关的失配位错、线位错及畴区的形貌已用扫描电子显微镜作了观察;与深能级相关的缺陷与其形貌间的关联也已用实验说明。对于高有序GaAs／Si外延膜来说，其与离域相关的主发光峰的强度对温度的变化服从阿兰纽斯方程，而对低有序的GaAs／Si外延膜来说，其与局域相关的主发光峰的强度对温度的变化关系则遵循对无定型半导体才成立的另一种方程。

Studies on the Correlation between Morphologies and Defects Related to Deep Levels in GaAs Epilayers Grown on Si

There exist the interfacial mismatch strains and high density structural defects in GaAs heteroepilayers grown on Si (GaAs/Si) because of a large misfit of the lattice constants and a large difference in linear thermal expansion coefficient between GaAs and Si materials. Our experiments show that the disordering at GaAs /Si epilayers strongly depends on their growth condition, especially on the As] /Ga] ratio. The morphologies of misfit dislocations, threading dislocations and texture regions, related to disordering at GaAs/Si samples, have been observed by using a scan electron microscope. The correlation between morphologies and defects, related to deep levels, has been demonstrated. For the GaAs/Si epilay ers with high or low order degree the variations of temperature versus 1ntensities of the dominant photoluminescence peaks,related to delocalized or local1zed defects, should satisfy an Arrhenius equation or a relation valid for amorphous semiconductors. respectively.