High-excitation photoluminescence in GaN: Hot-carrier effects and the Motttransition

Photoluminescence under intense excitation is studied in GaN. As the excita tion density increases, we show the Mott transition between an excitonic re combination to a plasma-type recombination. The carrier density at the Mott transition is given. At and above the Mott density, we show that the carri er temperature is higher than the lattice temperature. The energy relaxatio n of the hot plasma is shown to be dominated by LO-phonon emission. Coulomb screening and band-gap renormalization are observed from the photoluminesc ence peak position and the measured renormalization factor is in good agree ment with elementary many-body theory. Finally the dependence of the Mott d ensity on carrier temperature is shown to follow a Debye-Huckel model. [S01 63-1829(99)10727-6].