Subpicosecond time-resolved Raman studies of LO phonons in GaN: Dependence on photoexcited carrier density

Abstract

Subpicosecond time-resolved Raman spectroscopy has been used to measure the lifetime of the LO phonon mode in GaN for photoexcited electron-hole pair density ranging from 1016to2×1019cm−3. The lifetime has been found to decrease from 2.5ps, at low density, to 0.35ps, at the highest density. The experimental findings should help resolve the recent controversy over the lifetime of LO phonon mode in GaN.