T-matrix approach to equilibium and nonequilibrium carrier-carrier scattering in semiconductors

An analysis of strong-coupling effects in carrier-carrier scattering in electron-hole plasmas in semiconductors is presented. The conventional approach to scattering and dephasing rates is based on the Born approximation (a scattering cross section proportional to the square of the dynamically screened interaction potential), and is strictly valid only in the limit of the weakly coupled quantum plasma. Otherwise, strong correlations are expected to become important in the scattering quantities. Therefore, we perform a thorough analysis of scattering rates in the framework of the statically screened T-matrix (ladder) approximation. We solve the two-particle Schr\"odinger equation and provide explicit results for the carrier-carrier scattering rates in equilibrium as well as for optical excitation conditions. Numerical results for GaAs show evidence of significant deviations from the common Born approximation. Finally, dynamic screening effects are included approximately.