Structural and electronic properties of the Al-GaAs(110) interface

Abstract

Studies of both the structural and electronic properties of the Al-GaAs(110) interface are presented. It is found that the generally accepted relaxed GaAs(110) surface geometry is energetically unfavorable when the interface with Al is formed. The energy released from the interfacial back relaxation is more than 0.35 eV/(surface atom). Many of the salient features found here are consistent with a previous calculation of the Al-GaAs interface using a jellium model for Al. The presence of a high density of continuum states in the semiconductor energy gap is not sensitive to the interfacial structures, but the details are structure dependent. Estimates of the decay length and density at the Fermi level of the metal-induced gap states for the ideal interface are in good agreement with those from the jellium-model calculation. A new feature, absent in the jellium model, is the formation of Al—As bonds, which substantially reduces the density of states near the top of the valence band.