Band structure of highly mismatched semiconductor alloys: Coherent potential approximation

Abstract

The many-impurity Anderson model is applied to compound semiconductor alloys in which metallic anion atoms are partially substituted by highly electronegative atoms at low concentrations. The interaction between the localized states derived from the electronegative atoms and the Bloch states of the semiconductor matrix is treated in a single-site coherent-potential approximation. The solution for the Green's function provides dispersion relations and broadenings for the conduction-band states. The calculations validate the dispersion relations previously obtained from the two-level band anticrossing model. The restructured dispersion relations and optical absorption coefficient are calculated and compared with experimental results of ${\mathrm{GaAs}}_{1\ensuremath{-}x}{\mathrm{N}}_{x}$ alloys.