X-Ray Photoelectron Spectroscopy Study of Pt-Oxide Thin Films Deposited by Reactive Sputtering Using O2/Ar Gas Mixtures

Abstract

Thin-film oxides of Pt were grown reactively by rf magnetron sputtering and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Oxygen incorporation of the films was adjusted by controlling the oxygen mixing ratio (OMR). XRD reflections indicated that these samples have an amorphous structure without crystalline ordering of the Pt–O phases. SEM pictures showed that the formation of protrusions appear under the condition of large OMR. The XPS spectra revealed 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 eV, implying that the Pt oxide thin films are composed of PtO grains and intermediate oxides of PtO and PtO₂.