Structural and Electronic Properties of Sulfur-Passivated InAs(001) ( 2×6 ) Surface

The structural and electronic properties of S-passivated InAs(001)-(2×6) and InAs(001)−(2×1) surfaces are studied by first−principles total-energy calculations. Based on the calculated adsorption energies and electronic properties, we propose that the reconstruction of a S-treated InAs(001) surface should be InAs(001)–(2×6)S rather than InAs(001)−(2×1)S. This is similar to the adsorption behavior of S on a GaAs(001) surface. The Fermi level of an InAs(001)−(2×6)S surface exists above the conduction band minimum by 371 meV and the energy gap becomes 0.145 eV smaller than the clean surface. A strong surface electron accumulation layer is formed and downward band bending is increased, which is in good agreement with recent experiments.