GAAS SURFACE MODIFICATION BY ROOM-TEMPERATURE HYDROGEN PLASMA PASSIVATION

The role of hydrogen atoms in enhancing photoluminescence (PL) intensity of native-oxide-contaminated GaAs during room temperature, short-time exposure to a H-2 plasma is studied. Room-temperature D2 plasma passivations, annealing experiments in vacuum at 400-degrees-C, D atom depth profiling with secondary ion mass spectroscopy, and chemical etching of residual surface oxides after passivation are all consistent with a reduction in surface recombination velocity leading to enhanced PL. By contrast, passivation of deep level defects in bulk GaAs cannot account for all the observations. The passivated surface is stable up to 400-degrees-C in vacuum for at least an hour with only a slight reduction in PL intensity. Thus, it is possible to reactivate inadvertently neutralized donors and acceptors after passivation without affecting the reduction in surface recombination velocity.