超晶格（Ge_xSi_（1－x）1／（Si）_m（001）的电子能带结构

采用紧束缚的重整化方法计算了超晶格（ＧｅｘＳｉ１－ｘ）１／（Ｓｉ）ｍ（００１）的基本带隙及其导带底在布里渊区中的位置在Ｘ＝０．０１～０．１范围内随Ｘ的变化情况以及当Ｘ＝０．０１时随硅层层数ｍ的变化情况。计算结果表明，在ｘ＝０．０１～０．１范围内，ｘ对导带底位置基本上没有影响，导带底位置主要由硅层层数ｍ决定，并可根据布里渊区折叠计算得到。由此提出，可以制成类似于（ＧｅｘＳｉ１－ｘ）１／（Ｓｉ）ｍ（００１）形式的超晶格，而获得准直接能隙结构的材料，以提高其光的发射和检测能力。关键词：

Electronic Energy Band Structures of Superlattices (Ge_xSi_(1-x)_1 /Si_m (001 )

By using the renormalized method in tightbinding frame, the fundamental energy gap and the position of the conduction band bottom in the Brillouinzone are calculated for superlattices (GexSi1-x)1/Sim as functions of the alloy composition x(in x=0.01～0. 1 range) and the silicon layer number m (for x=0. 01 ).The results show that,in x=0. 01～0.1 range,the position of the conduction bandbottom is hardly dependent on the alloy composition x but mainly dependent on the St layer number m and can be determined by Brillouin zone folding. It is suggested that the improvement of the light emissivity and detectability can be attained through fabricating a type of superlattices like (GexSi1-x)1/Sim to turn the indirectgap structure into the direct (or pseudodirect) gap structure.