Analysis of ellipsometric and thermoreflectance spectra for P-based III-V compounds GaP and InP

Spectroscopic-ellipsometry (SE) and thermoreflectance (TR) spectra of GaP and InP are presented. Both measurements are carried out on the same samples in the 1.4-5.6-eV photon-energy range at room temperature. The measured SE and TR spectra reveal distinct structures at energies of the E(0), E(0) + Delta(0), E(1), E(0)(,), E(2) and E(2) + delta critical points. The Gamma(8)(v) --> X(6)(c) indirect-gap peak at 2.25eV can also be clearly seen in the TR spectrum of GaP. These spectra are analysed based on a simplified model of the interband transitions. The results agree well with the experimental SE and TR data over the entire range of photon energies.