Sulfur-modified surface of InP(001): Evidence for sulfur incorporation and surface oxidation

A photoemission study was performed in order to obtain structural and chemical information on a sulfurized InP(001) surface by using both high-resolution SXPS/XPS and polar angle scanned photoelectron diffraction (XPD). Theoretical simulations of the angular distribution curves (ADCs) were carried out on the level of single scattering cluster calculations. The ADCs of the S 2p core level of sulfur on InP(001) clearly indicate partial incorporation of the sulfur onto phosphorus lattice sites of the bulk InP structure. Persistence of sulfidic S species against UV/ozone exposure also suggests subsurface sulfur on InP(001). The sulfur-passivation may significantly reduce the amount of surface oxidation but cannot suppress it completely.