Theory of valence-band Auger spectra: GaAs(110)

In order to establish the utility of Auger line-shape analysis as a probe of local electronic structure at surfaces, we propose the study of GaAs(110) 1 ×{} 1. This surface is of interest because extensive theoretical studies of GaAs band structure, both bulk and surface, are available, because the 1 ×{} 1 nature of this surface's "reconstruction" permits a relatively unambiguous determination of its atomic geometry, and because the local densities of states (LDOS's) on the Ga and As atoms are very different. We calculate the Ga and As M₁M4,5V and M2,3M4,5V Auger line shapes for GaAs(110) and show that they differ considerably from one another, reflecting the differing angular-momentum compositions of the Ga and As LDOS's and the facts that valence s-electron emission is favored in the M₁M4,5V case while s- and p-electron emission are roughly equally weighted in the M2,3M4,5V lines.