Nonthermal carrier dynamics in AlxGa1-xAs/GaAs quantum wells

We present new time-resolved measurements that demonstrate the effect of injected carrier densities on carrier-carrier scattering rates of highly nonequilibrium carrier distributions in the p-doped Al0.32Ga0.68As/GaAs quantum wells with well width of 5 and 3 nm. The spectra at high densities (greater than or equal to 10(10) cm(-2)) demonstrate that the initially narrow electron distribution is altered in a time less than or equal to the LO phonon emission time as the result of rapid carrier-carrier scattering. At about the same excitation density (similar to 10(10) cm(-2)), the carrier-carrier scattering rate is faster in 3 nm quantum wells in comparison to 5 nm wells. Our results also indicate that carrier-carrier scattering becomes as significant as LO phonon emission at density of about 1 X 10(10) cm(-2) in the 5 nm quantum wells. (C) 2000 Elsevier Science B.V. All rights reserved.