形变Si,Ge中的深能级

对生长在合金衬底上的形变Si或Ge中由替位原子或空位缺陷产生的深能级进行了研究。其中形变体材料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出。结果表明,晶格中的形变使原来类p的T₂能级发生分裂,其数值随形变的增加而增大。形变还造成Si和Ge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。 关键词：

DEEP LEVELS IN STRAINED Si AND Ge

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