Phonon lifetimes and phonon decay in InN

We report on the Raman analysis of $A_1\left(\mathrm{LO}\right)$ (longitudinal optical) and $E_2$ phonon lifetimes in InN and their temperature dependence from 80 to 700 K. Our experimental results show that among the various possible decay channels, the $A_1\left(\mathrm{LO}\right)$ phonon decays asymmetrically into a high energy and a low energy phonon, whereas the $E_2$ phonon predominantly decays into three phonons. Possible decay channels of the $A_1\left(\mathrm{LO}\right)$ phonon may involve combinations of transverse optical and acoustic phonons. Phonon lifetimes of 1.3 and 4 ps were measured at 80 K for the $A_1\left(\mathrm{LO}\right)$ and the $E_2$ phonons, respectively. This rather long $A_1\left(\mathrm{LO}\right)$ phonon lifetime suggests that hot phonon effects will play a role in InN for carrier relaxation.