Dependence of Optical Properties of Semiconductor Alloys on Long Range Order, Strain and Pressure

Many III-V semiconductor alloys exhibit spontaneous (111) alternate monolayer ordering when grown from the vapor phase. We have studied theoretically the ordering induced changes in the optical properties of the semiconductor alloys. We descirbe (i) the change of the band gap .delta.Eg and the valence band splitting .delta.E12 as functions of the long range order parameter .eta., (ii) theconsequence of coexistence of (001) epitaxial strain and (111) chemical ordering on the optical properties, (iii) optical anisotropy and spin polarization effects in the ordered alloy, (iv) theory of reflectance-difference spectroscopy in ordered alloy, and (v) the ordering-induced changes on high energy E1 and E2 transitions. Specific experimentally testable predictions are listed in thesummary section.