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+Δ0, E 1, E 0', E 2 and E 2+δ critical points. The Γ 8 v →X6 c indirect-gap peak at 2.25 eV can also be clearly seen in the TR spectrum of GaP. These spectra are analyzed 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.