X-ray photoelectron spectroscopy study of Pt-oxide thin films deposited byreactive sputtering using O-2/Ar gas mixtures

Thin-film oxides of Pt were grown reactively by rf magnetron sputtering and characterized by X-ray diffraction (XRD), scanning electron microscopy (SE M) and X-ray photoelectron spectroscopy (XPS). Oxygen incorporation of the Rims was adjusted by controlling the oxygen mixing ratio (OMR). XRD reflect ions indicated that these samples have an amorphous structure without cryst alline ordering of the Pt-O phases. SEM pictures showed that the informatio n of protrusions appear under the condition of large OMR. The XPS spectra r evealed chemical shifts of Pt 4f peaks, which are ascribed to two different oxidation states of Pt. The amounts of the energy shifts are 1.0 and 2.1 e V, implying that the Pt oxide thin films are composed of PtO grains and int ermediate oxides of PtO and PtO2.