Screening and exchange in the theory of the femtosecond kinetics of the electron-hole plasma

This work deals with the dynamics of the nonthermalized electron-hole plasma in the subpicosecond regime. We computed different collision rates (electron-electron, electron-hole, electron-phonon) and discussed the relative efficiency of the different processes for the cases of static or dynamic screening of the interaction. We also considered how the inclusion of the exchange affected the scattering amplitude and the collision rates. Calculations were based upon GaAs. We conclude that dynamic screening is crucial for electrons in the conduction band at a high plasma density [say, at densities above (1–2)×${10}^{16}$/${\mathrm{cm}}^3$], whereas it generally plays a minor role at low density and when descibing hole dynamics. The excitation of heavy holes into the light-hole band by collisions with the conduction electrons is discussed in heavily p-doped GaAs.