CHEMICAL BONDING STUDIES ON UV OZONE-TREATED AND (NH4)(2)S-TREATED INP(001) SURFACES BY X-RAY PHOTOELECTRON-SPECTROSCOPY AND X-RAY-INDUCED AUGER-ELECTRON SPECTROSCOPY/

X-ray photoelectron spectroscopy (XPS) and x-ray-induced Auger electro n spectroscopy (XAES) have been applied to characterize the surface ch emistry of InP(001) after ex situ treatment with ozone or with (NH4)(2 )S solution. Both high-resolution chemical shifts and the Auger parame ter concept were used for the identification of chemical species. Afte r UV/ozone exposure, indium oxide and two phosphate types (orthophosph ate and metaphosphate) were found on the InP surface. Upon annealing t he phosphates desorb first, followed by the oxide. On (NH4)(2)S-treate d InP surfaces three sulphur species were observed and identified as t wo 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 su rface Fermi energy position accompanying the surface sulphurization we re established to correlate with the annealing behaviour of the polysu lphidic species found at the InP surface.