The electronic structure of point defects in semiconductor alloys: simplified approximations

The authors present a simplified tight-binding-based coherent-potential approximation (CPA) formalism for the host electronic structure of semiconductor alloys (e.g. Ga1-xAlxAs). Several schemes to locate the gap level due to point defects are discussed. In particular, they introduce a novel scheme: the deep-level approximation. They also point out that the vacancy results in the CPA are identical with the simpler virtual-crystal approximation. They discuss their results by presenting numerical results in Ga1-xAlxAs and GaAs1-xSbx