Calculations of Optical Properties for Quaternary III-V Semiconductor Alloys in the Transparent Region and Above (0.2-4.0eV)

The modeling of the spectral behavior of the refractive indices of the binary, ternary and quaternary III-V semiconductor alloys in the energy range from 0.2 to 4eV, including the transparent region, is presented. The extended model of interband transition contributions incorporates not only the fundamental absorption edge contribution to the dielectric function, but also contributions from higher energy and indirect transitions. It is demonstrated that indirect energy transitions must be included in the calculations of the complex dielectric function of the material in the transparent region. Indirect transitions from different critical points in the Brillouin zone are treated separately. The comparison between the theoretical refractive indices and the experimental data for AlGaAsSb, AlGaInAs, AlGaInP, GaInAsSb, and GaInPAs alloys is presented. These calculations have been applied to the design of Bragg mirrors with the highest refractive index contrast for heterostructure lasers.