The chemical state of (NH4)2S treated (100)GaAs surfaces exposed to ambient conditions for several days was correlated with barrier height measurements. Surface chemistry was characterized by Auger electron spectroscopy and barrier heights were calculated from C-V measurements obtained with a Hg probe. Results show that surfaces are chemically and electrically unstable for several hours following the sulfide treatment. The chemical and electrical states continually changed during ambient exposure up to 300 hours. Although strictly speaking, the surfaces were not passivated, the presence of sulfur did inhibit the formation of Ga and As oxides and the incorporation of carbon. In addition, stable, low barrier heights were observed after ambient exposure for several hours. Barrier heights from C-V measurements using deposited Au and Al contacts were compared to the barrier heights obtained with a Hg probe.
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