应变致能带分裂对Si_（1－x）Ge_x应变层中重掺杂禁带窄变的影响

Effects of Strain Induced Splitting of Energy Bands on the Bandgap Narrowing Due to Heavy Doping in Strained Si_(1-x)Ge_x Layers

针对应变Ｓｉ１－ｘＧｅｘ的应变致能带分裂及重掺杂对裂值的影响，提出了多子双带结构的等价有效简并度模型和有关算法。模型中考虑了非抛物线能带结构。应用该模型，计算了赝形生长在（１００）Ｓｉ衬底上的Ｓｉ１－ｘＧｅｘ应变层的重掺杂禁带窄变，发现当掺杂超过一定浓度（对于ｐ型和ｎ型合金，该浓度分别约为１．９×１０１９ｃｍ－３和３．５×１０１９ｃｍ－３）后，它在某一Ｇｅ组分下得到极大值，而当掺杂低于这个浓度时，它则随Ｇｅ组分的增加单调下降。文中还将计算结果与其它未细致考虑应变致能带分裂因素的理论工作进行了比较。

o take the effects of strain induced splitting of energy bands into account when calculating the bandgap narrowing (BGN) due to heavy doping in pseudomorphic Si1-xGex layers grown on (100) Si substrate, an equivalent effective degeneracy (EED) model is proposed for the majority carrier double-band structure of the strained alloy. The results are compared with those taken from other theoretical works, in which the influences of strain induced splitting of energy bands were ignored, and show that there is a maximum value of the BGN at a certain Ge fraction if dopant concentration exceeds about 1. 9 X 1019 cm-3 and 3. 5 X 1019 cm-3 for the p-and n-type alloy respectively, and that, otherwise, it will decrease continuously as Ge fraction increases.