Abstract: Deep levels of vacancy and substitutional impurity atoms in a strained Si_1-xGe_x alloy grown on Si, Ge and alloy substrates are investigated. The band structures of the strained alloy 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 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.

Key words: substitutional defect, Green's function method, deep level, strain