ADSORPTION AND DESORPTION OF SULFUR ON A GAAS (001) SURFACE BY H2S EXPOSURE AND HEAT-TREATMENT

The adsorption and desorption of sulfur on a GaAs (001) surface was studied using in situ Auger electron spectroscopy and reflection high-energy electron diffraction (RHEED). The H2S-treated surface showed a (2 x 1) sulfur-terminated structure, with the sulfur considered to be a few monolayers thick. RHEED patterns showed that the (2 x 1) reconstruction changed into an arsenic-stabilized (2 x 4) structure when heated to 590-degrees-C under an arsenic flux. A sulfur Auger signal on the H2S-treated surface was found to completely disappear upon heating. These data show that H2S exposure is appropriate for preparing a sulfur-terminated surface and that high-quality crystal regrowth is possible on the surface after being heat treated.