Phonon linewidth in III-V semiconductors from density-functional perturbation theory

In this work we present an ab initio calculation of the Raman linewidth of transverse and longitudinal phonon in zinc-blende semiconductors GaAs, AlAs, GaP, and InP. We propose a simple approximation that permits us to calculate the longitudinal linewidths with the same computational effort as the transverse ones. The microscopic mechanisms responsible for the decay are analyzed and discussed. The temperature dependence of the linewidths is computed. Our results are in good agreement with available experimental data up to room temperature for both transverse and longitudinal optical modes and give reliable predictions in materials difficult to study experimentally.