Reaction of oxygen with in situ H2S-treated GaAs (001) surfaces

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Abstract
The reaction of oxygen with H2S‐treated GaAs (001) surfaces was studied using Auger electron spectroscopy and reflection high‐energy electron diffraction. GaAs surfaces in situ treated with H2S gas were exposed to pure oxygen gas with and without simultaneous light illumination of a halogen lamp. It was shown that the oxygen uptake on a H2S‐treated surface is much less than that on an untreated bare GaAs surface. Surfaces exposed to oxygen were heated in an ultrahigh‐vacuum environment in order to study the desorption of the reacted oxygen. The oxygen Auger signal was found to easily disappear when the surface was heated to 520 °C, leaving sulfur atoms on the surface. The oxide formed on a bare GaAs surface with light illumination was found to be relatively thick; it did not desorb completely until it was heated to about 550 °C. These results indicate that oxide on a H2S‐treated surface is formed only on the top surface.