Intervalley scattering times from the rigid-pseudoion method

We have used the rigid-pseudoion method (with q-dependent matrix elements and a realistic non-parabolic band structure) to calculate the lifetimes of electrons at the L- and X-points in GaAs as a function of temperature (L: 2.2±0.5 p5, X: 130±20 fs at room temperature). The contribution of the TA phonons to LF-scattering explains the discrepancy between the experiments of Shah and Kash, performed at two different temperatures. About 80% of the carriers at X scatter into the L-valleys. The intervalley scattering times in the F-valley for electrons with an energy of 165 meV above the L-point are found to be 750±100 fs at helium temperatures (100 fs for electrons with an energy of 270 meV). These results compare favorably with recent femtosecond and CW laser experiments.