Experimental and theoretical study of dephasing processes in the kinetics of photoexcited carriers in GaN

The scattering and dephasing processes that accompany the initial photoexcitation of electron-hole pairs in the semiconductor GaN are studied by sub-picosecond time-resolved photoluminescence. The rise time of the carrier recombination at the band edge after excitation 750 meV above the band gap is analyzed as a function of initial photoexcited carrier density and sample temperature. To elucidate the findings, simulations were performed based on a two band model with a non-parabolic conduction band and using a generalized Monte-Carlo technique. Results showed a small dependence in the rise time on the initial carrier density but a strong dependence on the sample temperature, where simulation and experiment scaled proportionately. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)