Nonthermal carrier dynamics in Al xGa 1− xAs/GaAs quantum wells

Abstract

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 Al 0.32Ga 0.68As/GaAs quantum wells with well width of 5 and 3 nm. The spectra at high densities (≥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 (∼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 1×10 10 cm −2 in the 5 nm quantum wells.