Surface and interface states for GaAs(100) (1×1) and (4×2)-c(8×2) reconstructions

Abstract

Low energy cathodoluminescence spectroscopy measurements of GaAs(100) surfaces prepared by thermal desorption of an As passivation layer reveal deep level transitions localized at the clean surfaces and metallized interfaces. These surface and interface state features extend from 0.7 to 1.3 eV and exhibit subtle differences between the As-rich (1×1) and Ga-rich (4×2)-c(8×2) reconstructions. Both Au deposition and subsequent annealing induce additional deep level emissions which appear relatively unchanged between these two reconstructions. In contrast, Al deposition introduces new features which depend significantly upon starting surface stoichiometry and reconstruction. We discuss the formation and energies of these states in relation to reported variations in Fermi level stabilization. We conclude that surface stoichiometry and atomic bond configuration are a significant factor in formation and evolution of electrically active, deep level metal-GaAs(100) interface states.