Effect of carrier-carrier interaction on intervalley transfer rates of photoexcited electrons in GaAs.

Abstract

The intervalley transfer of carriers photoexcited by a 2.04-eV laser pulse and their response to a 500-V/cm field in GaAs is examined for two excitation levels of 5\ifmmode\times\else\texttimes\fi{}${10}^{16}$ and ${10}^{18}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$. It is found that the transfer rates are not affected by electron-hole or electron-electron interactions at low excitation levels. At high excitation levels the electron-hole interaction accelerates the return rates to the central valley and provides an important energy-loss channel for the electrons. In response to a 500-V/cm field, the electrons exhibit very small velocities during the first 2 ps. At times beyond 4 ps, the velocities are smaller for higher electron densities.