Time-resolved photoluminescence of dense electron-hole plasmas in In-Ga-As-P films

Time-resolved photoluminescence spectra of dense electron-hole plasmas in In-Ga-As-P films have been measured with 200-ps resolution, at room temperature. The carrier density, temperature, and band-gap energy are determined as a function of time delay following excitation and of initially excited carrier density. We observe the theoretically predicted band-gap renormalization. The carrier temperature is found to equilibrate to a temperature near the lattice temperature within 200 ps after excitation. Initially photoexcited carrier densities of more than 5×1020 cm-3 are found to decay to less than 6×1018 cm-3 within 200 ps. Evidence is presented which indicates that expansion of the electron-hole plasma is an important mechanism in this decay. The density decay after 200 ps is due to a combination of Auger and radiative recombination.