Central role of electronic temperature for photoelectron charge and spin mobilities in p⁺-GaAs

The charge and spin mobilities of minority photoelectrons in p⁺-GaAs are determined by monitoring the effect of an electric field on the spatial profiles of the luminescence and of its polarization. By using electric fields to increase the photoelectron temperature T_e without significantly changing the hole or lattice temperatures, the charge and spin mobilities are shown to be principally dependent on T_e. For T_e > 70 K, both the charge and spin mobilities vary as Te-1.3, while at lower temperatures this changes to an even more rapid Te-4.3 law. This finding suggests that current theoretical models based on degeneracy of majority carriers cannot fully explain the observed temperature dependence of minority carrier mobility.