Carrier-carrier scattering in GaAs/AlxGa1-xAs quantum wells

We have studied carrier dynamics in highly nonequilibrium two-dimensional (2D) carrier distributions generated with femtosecond laser pulses in p-doped GaAs/Al0.32Ga0.68As quantum wells at photoexcited carrier densities between 10(9) and 10(11) cm(-2). The initially nonthermal carrier distribution is quickly broadened due to inelastic carrier-carrier scattering, with the broadening rate increasing as carrier density is increased. Measurements of the unrelaxed peak height in the hot electron-neutral acceptor luminescence spectra are compared with calculations of the carrier distribution using integration of the 2D dynamically screened Boltzmann equation. Our results indicate that carrier-carrier scattering becomes as significant a scattering mechanism as LO-phonon emission at density of about 10(10) cm(-2).