Temperature dependence of the interband critical-point parameters of InP

Abstract

Spectroscopic ellipsometry has been used to measure the dielectric function \ensuremath{\epsilon}(\ensuremath{\omega}) of InP from 30 to 750 K in the 1.3--5.5-eV photon-energy region. By performing a line-shape analysis of the structures observed, the temperature dependence of the interband critical-point parameters (strength, threshold energy, broadening, and excitonic phase angle) has been determined. The decrease in energy and the increase in broadening with increasing temperature are analyzed in terms of averaged frequencies of phonons giving rise to the renormalization of the band states due to electron-phonon interaction.