形变的SiGe合金中的深能级

DEEP LEVELS IN STRAINED SiGe ALLOY

该文对生长在Ｓｉ、Ｇｅ及其合金衬底上形变的Ｓｉ１－ｘＧｅｘ合金中由替位原子或空位缺陷产生的深能级进行了研究．其中形变合金的电子结构用经验的紧束缚方法进行计算，缺陷能级采用格林函数法进行计算．结果表明，晶格中的形变使原来类ｐ的Ｔ２能级发生分裂．形变还造成合金的价带顶有较大的上升，从而使某些杂质的缺陷能级由深能级变为共振能级．

Deep levels of vacancy and substitutional impurity atoms in a strained Si1-xGex alloy grown on Si, Ge and alloy substrates are investigated. The band structures of the strained alloy are calculated by using the empirical tightbinding method. The method of Green's function has been nsed to calculate the defect levels. The results show that the triply-degenerate p-like T2 level of the defect in bulk Si or Ge splits into two levels due to the strain. Owing to the strain, the valence band maximum of the alloy shifts upward, hence some deep levels in the bulk might transform to resonant ones.