LIGHT-INDUCED REACTIVATION OF SHALLOW ACCEPTORS IN HYDROGENATED N-TYPE ALXGA1-XAS

The stability of the hydrogen-shallow acceptor complex in hydrogenated silicon-doped direct-gap AlxGa1-xAs is studied by low-temperature photoluminescence measurements. The shallow accepters are passivated by hydrogen diffusion and the hydrogen-passivated accepters are reactivated by a prolonged illumination with above-band-gap photons. The light-induced reactivation is virtually athermal (it is observed at cryogenic temperatures) and reversible (the minority accepters recover their initial passivated state by heating the sample to temperatures close to room temperature). A model describing the radiative recombination processes observed in the studied samples is presented and the relative concentration of shallow accepters is deduced from the intensity of the photoluminescence bands. The light-induced reactivation process of C-As accepters follows a first-order kinetics with a dissociation frequency linearly dependent on the illumination intensity.