RATE-EQUATIONS FOR THE STUDY OF FEMTOSECOND INTERVALLEY SCATTERING IN COMPOUND SEMICONDUCTORS

We present solutions to a set of rate equations for the electron dynamics after photoexcitation by a 2.0-eV laser in GaAs and InP. Results obtained, although simpler than full Monte Carlo solutions, closely follow the experimental data and provide insight into intervalley scattering. Calculations show that the net return time of electrons from the satellite L valleys into the GAMMA-valley is not limited by the intervalley scattering rate, but is instead limited by the polar-optic-phonon scattering rate within the GAMMA-valley. This shows that the time-dependent mobility and luminescence experiments depend on the L-valley depopulation rate, which differs from the L --> GAMMA-intervalley scattering rate. Results further suggest that the GAMMA --> L scattering rate is faster than the polar-optic-phonon scattering rate.