摘要
在紧束缚的框架下,利用重整化方法计算了超晶格(Ge_2)_1/(GaAs)_m(110)(m=1-20)的电子能带结构。计算结果表明,对不同m的超晶格(Ge_2)_1/(GaAs)_m(110) 都具有间接能隙结构,而且间接导带底的电子状态具有明显的二维特性。单层超晶格(Ge_2)_1/(GaAs)_1(110)具有非常小的间接和直接禁带宽度。当GaAs层的层数m逐渐增加时,导带的电子状态逐渐由三维特性向二维特性过渡,但是这一过渡对布里渊区内的各点,情况都各不相同。超晶格导带底的横向色散关系当m≥10以后,基本上不再随m的增加而改变。
The electronic band structures of superlattices (Ge_2)_1/(GaAs)_m(110) with m=1-20 werecalculated by using the renormalization technique in tight-binding frame. The results show thatthe valence band top and the conduction band bottom of superlattice (Ge_2)_1/(GaAs)_m (110)are not at the same point in the Brillouin zone and the electronic states at the bottom of conductionband display distinct 2-dimensional character For the monolayer superlattice (Ge_2)_1/(GaAs)_1, both the indirect and direct forbidden bands are very narrow. As the number ofGaAs layers increases, the electronic states at the bottom of conduction band transit from 3-dimensional character to 2-dimensional character gradlually, and the degrees of the transitionsare different for each point in the Brillouin zone.The transverse energy dispersion of the conductionband remains unchanged when the number of the GaAs layer m increases, if m≥10.
基金
国家自然科学基金
关键词
Ge/GaAs
电子能带结构
禁闭效应
Carvier Confinement Effect
Folding of Brillouin Zone
Renormalization Technique
Superlattice
