Phonon Frequencies of InP Derived from Two‐Phonon Absorption

Abstract

AbstractInfrared absorption measurements have been performed on InP at various temperatures from 20 to 300 K in the spectral range from 370 to 700 cm−1 in which the absorption is due to two‐phonon absorption processes. The ir absorption peaks as well as the second‐order Raman scattering data by Alfrey and Borcherds are analyzed in terms of critical point phonon frequencies. The consistency of the derived phonon frequencies is checked from different points of view, above all by using the temperature dependence of the peaks. Especially the LA frequencies turn out to be larger than those of earlier assignments indicating a smaller frequency gap between the acoustic and optical phonons than that calculated by Talwar and Agrawal. Recent neutron scattering data support the assignment given here.