第一性原理研究应变Si/(111)Si1-xGex能带结构

基于密度泛函理论框架的第一性原理平面波赝势方法对双轴应变Si/(111) Si_1-xGe_x(x=0.1—0.4)的能带结构进行了研究，结果表明：导带带边六度简并没有消除；应变部分消除了价带带边的简并度；导带带边能量极值k矢位置和极值附近可由电子有效质量描述的能带形状在应变条件下几乎不变；价带极大值附近可由空穴有效质量描述的能带形状随着x有规律地变化. 此外，给出的禁带宽度与x的拟 关键词： 应变硅 能带结构 第一性原理

Band structure of strained Si/(111)Si1-xGex: a first principles investigation

There has been a great interest in the strained Si CMOS technology lately, especially the modification of band structures which provides a theoretical basis for the design of the high-speed and high-performance devices and circuits. Calculations were performed on the band structures in strained Si/(111)Si_1-xGe_x(0≤x≤0.4) by the first-principle pseudopotential approach of the plane wave based upon the density functional theory. It was found that the conduction band (CB) edge is characterized by the six valleys all the same, that valence band (VB) edge degeneracies are partially removed and that the electron mass in CB is unaltered under strain while the hole mass decreases along the ［100］ direction with increasing x. In addition, the fitted dependence of bandgap on x are in good agreement with KP theoretical calculation, from which the quantitative data supply valuable references to the devices design.