CHEMICAL-STABILITY OF (NH4)(2)S-PASSIVATED INP(001) SURFACES - INVESTIGATIONS BY XPS AND XPD

UV/ozone supported surface oxidation of wet chemically cleaned and sul furized InP(001) was investigated using XPS in order to study the chem ical stability of (NH4)(2)S-passivated surfaces. Sulfur coverages of a bout one monolayer thickness were not sufficient to completely passiva te the InP surface against oxidation. Similar oxides of the substrate components were observed at the surfaces. Evidence for surface passiva tion was found in the chemical stability of incorporated sulfur (In-S bonds), the lower growth rate of the oxide layer and its reduced thick ness at comparably large UV/ozone exposures. The oxide layer was found to be amorphous at all stages of the oxidation process, as was proved by X-ray photoelectron diffraction.