HIGH-FIELD TRANSPORT IN SEMICONDUCTORS .2. COLLISION DURATION TIME

The collision duration time tau-CD (a short time scale < 10(-14) S) is estimated for an equilibrium nondegenerate semiconductor. For interaction with nonpolar optical phonons, it is shown that there is one common scale tau-CD for both the scattering-in and scattering-out integrals. This time is defined so that if tau-CD << tau (tau is the quasiparticle lifetime) subsequent scattering events do not interfere. We find that the best estimator for this time, which is independent of the temperature, is the Landau criterion proposed for metals.