Abstract

Semi-insulating GaAs with its native mid-gap defect EL2 reveals optical optical nonlinearities of different kinds at short pulse excitation: (i) intrinsic ones based on nonequilibrium free carriers, and (ii) photorefractive ones due to space-charge redistribution. The metastable properties of EL2 open novel possibilities for direct optical modulation of quasi-Fermi level by resonant excitation and quenching of EL2 defect at low temperatures.¹ This novel object—a light induced periodic structure of alternating areas with n- and p-type conductivity—needs deeper studies.

© 1994 IEEE