Dynamics of LO phonons in InN studied by subpicosecond time-resolved Raman spectroscopy

Abstract

AbstractThe phonon dynamics of both the A1(LO) and the E1 (LO) phonons in InN has been studied by time-resolved Raman spectroscopy on a subpicosecond time scale. From the temperature-dependence of their lifetimes, we demonstrate that both phonons decay primarily into a large wavevector TO phonon and a large wavevector TA/LA phonon consistent with the accepted phonon dispersion relationship for wurtzite InN. Their lifetimes have been found to decrease from 2.2 ps, at the low electron-hole pair density of5x1017cm-3 to 0.25 ps, at the highest density of2x1019cm-3. Our experimental findings demonstrate that carrier-density dependence of LO phonon lifetime is a universal phenomenon in polar semiconductors.