Chemical and structural characterization of GaSb(100) surfaces treated by HCl-based solutions and annealed in vacuum

Abstract
The surface preparation of GaSb(100), based on HCl solutions, was studied by x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The chemical and structural analysis by XPS and AFM indicates that the GaSb surface treated by HCl followed by a 2-propanol rinse leads to a 1 to 2 nm oxide layer on the surface. The resulting smooth surface is slightly antimony rich. Surfaces rinsed in deionized water, after HCl-based etching, possess a thicker overlayer, which is depleted of antimony. The surface morphology becomes rough rapidly upon reexposure to air after the HCl/H2O treatment. Other etching processes, including a tartaric acid based etchant, were investigated. Tartaric acid-based etches yield a highly nonstoichiometric surface along with an inhomogeneous etching morphology. The rates of desorption of surface oxides were determined by XPS analysis under ultrahigh vacuum conditions and the typical temperatures of desorption for the constituent chemical component comprising the surface layer were determined.