Hot-Electron Recombination at Neutral Acceptors in GaAs: A cw Probe of Femtosecond Intervalley Scattering

Abstract

The rates at which hot electrons scatter from the $\ensuremath{\Gamma}$ valley to the $L$ and $X$ valleys in GaAs have been measured as a function of electron energy. Scattering times are determined from the relative efficiency of recombination of hot electrons with neutral acceptors at low injected-carrier densities. Representative scattering times are ${\ensuremath{\tau}}_{\ensuremath{\Gamma}L}=540\ifmmode\pm\else\textpm\fi{}120$ fsec for 0.48-eV electrons and ${\ensuremath{\tau}}_{\ensuremath{\Gamma}X}=180\ifmmode\pm\else\textpm\fi{}40$ fsec for 0.58-eV electrons. Our results enable us to reconcile the large range of scattering rates reported in other experiments and demonstrate the power of this cw probe to study subpicosecond electron dynamics.