Photoelectric memory effect in GaAs

Abstract

Experimental data are reported for the persistent photocapacitance quenching observed at 77 K in GaAs. This effect, which arises on the so-called oxygen (or EL2) center in gallium arsenide, is explained by the existence of two states of this center. The physical parameters of these stable and metastable states are given: optical cross section, annealing, and electrical deexcitation. Assuming a large lattice relaxation for the metastable one, a physical model is given with a possible microscopic origin. Other striking memory effects, and especially photoconductivity, are shown to be simply explained by our model.