半导体异质结(111)面的界面偶极子及其对能带偏移的影响

本文采用紧束缚的界面键极性模型(interface-bond-polarity-model),计算了匹配的半导体异质结(111)面的界面偶极子,并将计算结果与(110)和(001)面的结果进行了比较,讨论了界面取向和界面成分对偶极子的影响。结果表明,对于两边同是Ⅲ-V族半导体或同是Ⅱ-Ⅵ族半导体的异质结,界面偶极子几乎不依赖于界面的取向和界面的组成,因此,能带偏移也基本上是各向同性的。对于两边由不同类型半导体组成的异质结,如Ⅱ-Ⅵ/Ⅲ-Ⅴ体系、Ⅲ-Ⅴ/Ⅳ和Ⅱ-Ⅵ/Ⅳ体系,混和的阴离子(111)界面给出的偶极子小于零,而混和的阳离子(111)界面给出的偶极子大于零,二者的平均值等于中性的(110)界面的偶极子。关键词：

INTERFACE DIPOLES FOR (111) SEMICONDUCTOR HETERO-JUNCTIONS AND THEIR INFLUENCES ON BAND OFFSETS

The interface dipoles for (111) lattice-matched semiconductor hererojunctions are calcula-ted employing the tight binding interface-bond-polarity model. The calculated results are com-pared with that of (110) and (001) interfaces. The effects of the interface orientation and the interface composition on the interface dipoles are discussed. It is shown that the dependence of the interface dipoles on the interface orientation and the interface composition is very weak tor isovalent heterojunctions, therefore the corresponding band offsets are almost isotropic; the anion-mixed (111) interface has a negative dipole and the cation-mixed (111) interface has a po-sitive one for nonisovalent heterojunctions, their average equals to the dipole of the nonpolar (110) interface.