Chemical bonding studies on UV/ozone‐ and (NH4)2S‐treated InP(001) surfaces by x‐ray photoelectron spectroscopy and x‐ray induced Auger electron spectroscopy

Abstract

AbstractX‐ray photoelectron spectroscopy (XPS) and x‐ray‐induced Auger electron spectroscopy (XAES) have been applied to characterize the surface chemistry of InP(001) after ex situ treatment with ozone or with (NH4)2S solution. Both high‐resolution chemical shifts and the Auger parameter concept were used for the identification of chemical species.After UV/ozone exposure, indium oxide and two phosphate types (orthophosphate and metaphosphate) were found on the InP surface. Upon annealing the phosphates desorb first, followed by the oxide. On (NH4)2S‐treated InP surfaces three sulphur species were observed and identified as two different sulphides and as a polysulphide (SS bond). The thermally most stable sulphur species was attributed to a sulphide with sulphur on a phosphorus site in the uppermost subsurface layer. Changes of surface Fermi energy position accompanying the surface sulphurization were established to correlate with the annealing behaviour of the polysulphidic species found at the InP surface.