Ensemble Monte Carlo simulation of intervalley scattering in AlxGa1-xAs

An ensemble Monte Carlo simulation of the femtosecond response of photoexcited electrons in indirect-gap AlxGa1-xAs is performed. The time evolution of electron populations in the conduction-band valleys is studied. By comparing with recent femtosecond infrared-absorption experiments, a value for the L-X intervalley deformation potential was derived through parameter fitting. The effect of binary phonon modes due to the alloy structure of the semiconductor is incorporated into the simulation of both the ultrafast scattering processes and the indirect photogeneration process. The value found for the L-X intervalley deformation potential, DXL=1.7±0.5×108 eV/cm, can be assumed as a lower bound for the deformation potential in GaAs.