Anomalous temperature dependence of photoelectron charge and spin mobilities in p+-GaAs

The effect of an electric field on the spatial charge and spin profiles of photoelectrons in p+-GaAs is studied as a function of lattice and electron temperature. The charge and spin mobilities of photoelectrons are equal in all conditions and exhibit the well known increase as the temperature is lowered. It is shown that this is related mainly to the electron statistics rather than the majority hole statistics. This finding suggests that current theoretical models based on degeneracy of majority carriers cannot fully explain the observed temperature dependence of minority carrier mobility.