应变Si_（1－x）Ge_x层本征载流子浓度和有效态密度的解析计算

计算了应变Ｓｉ１－ｘＧｅｘ层的本征载流子浓度及导带和价带有效态密度。用解析方法研究了它们与Ｇｅ组分ｘ和温度Ｔ的依赖关系。发现随Ｇｅ组分ｘ的增加，导带和价带有效态密度随之快速减小，而本征载流于浓度却随之而近乎指数式地增加。而且，温度Ｔ越低，导带和价带有效态密度随Ｇｅ组分ｘ的增加而减小得越快，而本征载流于浓度上升得越快。同时还发现，具有大Ｇｅ组分ｘ的应变Ｓｉ１－ｘＧｅｘ层，其用Ｓｉ相应参数归一化的导带和价带有效态密度及它们的积对温度Ｔ的依赖关系弱，而具有小Ｇｅ组分ｘ的应变Ｓｉ１－ｘＧｅｘ层，上述归一化参数对温度Ｔ的依赖关系强，这和目前仅有的文献［８］中，它们与温度依赖关系的定性研究结果相一致。

Analytical Calculations of Intrinsic Carrier Concentration and Effective State Densities in Strained Si1-x Gex Layers

In this paper, the intrinsic carrier concentration m and the conduction andxalence bands effective state densities Nc and Nv in strained Si1-xGex layers are calculated,and dependence of ni,Nc and Nv on the temperature T and the Ge fraction x are studied analytically. It is found that m increases quasi-exponentially whereas, Nc,Nv and the product of (Nc. Nv) decrease rapidly as the Ge fraction x increases. Furthermore, when temperature T becomes lower, the decreases of Nc,Nv and their product (Nc. Nv) become more rapid, and the increase of m becomesmore evident. In addition,it is also found that for the strained St,uM.Ge. layers with low Ge fraction x and with high Ge fraction x, the dependences of Nc,Nv and their product (Nc. N.)normalized by the relevant parameters in St on temperature T are strong and slight, respectively, which are consistent with the results in ref8].