k-space carrier dynamics in GaAs

Abstract

We investigate the k‐space scattering dynamics of carriers in GaAs by measuring the transient relaxation of an anisotropic population produced by a linearly polarized 9 femtosecond infrared pulse. The redistribution of carrier momentum is shown to occur in the first tens of femtoseconds after excitation, and the relaxation times are found to vary with carrier density, from 25 to 60 fs for a carrier density range from 8×10¹⁷ to 8×10¹⁶ cm⁻³. Our results indicate that carrier momentum is rapidly redistributed via carrier–carrier scattering, and the nature of the density dependence suggests that the scattering is mediated by a screened Coulomb interaction between the carriers.