Electronic properties of Sb deposited on GaAs(110) in the submonolayer coverage regime

We present theoretical calculations of the electronic structure of a Sb/GaAs(110) interface in a submonolayer deposition regime. We have studied two different structural models of the Sb islands on GaAs(110) corresponding to a coverage theta =0.625. A self-consistent first-principles pseudopotential method using density-functional theory within the local-density approximation has been used to calculate the minimum-energy atomic configuration of the Sb islands and of the GaAs substrate. In particular, we have determined the equilibrium geometry and the electronic properties of the Sb terrace edges. The terrace terminated with a Sb atom bonded to an As atom of the substrate is energetically favored with respect to the edge having the Sb atom bonded to a Ga substrate atom. In both cases there is a tendency of the Sb atom on the edge to move towards a site at which a threefold coordination can be reestablished by forming a bond with another atom of the substrate. This is achieved by red...