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本文采用经验LCAO紧束缚方法,对晶格失配的Si和Ge所形成(Si)_(?)/(Si_(1-x)Ge_x)_(?)(100)(n=1～10)形变层超晶格进行了电子结构的计算。在计入晶格常数的变化对第一近邻相互作用的影响后,给出了超晶格能隙和导带底位置随层数的变化,讨论了能带折迭和能带边不连续对Si/Ge能隙直接间接性的影响。根据形变引起的Si和Ge导带底的反转,说明了Si层中二维电子气的现象。形变后的能带,与可得到的实验和其它理论的结果比较符合。本文还计算讨论了有效质量和界面态的问题。
In this paper, the empirical LCAO tight binding method is used to investigate the effect of lattice mismatch between Si and Ge on Si (100) (n = 1 ~ 10) Deformation layer superlattice electronic structure calculations. After taking into account the influence of the change of lattice constant on the first-neighbor interaction, the variation of the superlattice energy gap and the bottom position of the conduction band with the number of layers is given. The relationship between band-folding and discontinuous Effect of Si / Ge energy gap direct immediacy. According to the inversion of the conduction band of Si and Ge at the bottom caused by the deformation, the phenomenon of two-dimensional electron gas in the Si layer is described. The energy band after deformation is in good agreement with the available experimental and other theoretical results. This article also calculates the problem of effective mass and interface states.