Effects of Na2S and (NH4)2S edge passivation treatments on the dark current-voltage characteristics of GaAs pn diodes

The dark current-voltage characteristics of GaAs pn homojunctions whose surfaces have been passivated with Na2S and (NH4)2S chemical treatments have been investigated. Reductions in 2kT perimeter recombination currents by a factor of 3.2 were obtained for the two treatments. A shunt leakage, observed at low forward bias for the Na2S treated devices, is virtually eliminated with the (NH4)2S treatment. It is also shown that even the high quality, large area (0.25 sq cm) pn diodes used in this study are dominated by 2kT edge currents before passivation.