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 $M_1{M}_{4,5}V$ and $M_{2,3}{M}_{4,5}V$ 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 $M_1{M}_{4,5}V$ case while $s$- and $p$-electron emission are roughly equally weighted in the $M_{2,3}{M}_{4,5}V$ lines.