First-principles study of sulfur passivation of GaAs(001) surfaces

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Abstract
The structural and electronic properties of Ga- and As-terminated GaAs(001)-(1×1) surfaces adsorbed with a monolayer of sulfur have been investigated by using the ab initio pseudopotential method. We found that S atoms adsorb on the bridge site on both GaAs surfaces. It is shown that the surface-state density within the GaAs energy gap is markedly reduced by the S adsorption on the Ga-terminated surface. The reduction of surface states is not found at the As-terminated surface, since an As-S antibonding state appears within the gap. The mechanism of the S passivation has been investigated.