Preparation of PtO and α-PtO₂ Thin Films by Reactive Sputtering and Their Electrical Properties

Abstract

Pt oxide thin films are prepared by sputtering Pt target in an atmosphere containing Ar and O 2 gases. Polycrystalline PtO and α-PtO 2 films are obtained in O 2 flow ratio regions of 30–50% and 80–100%, respectively, at a substrate temperature of 300°C. Electrical resistivity of the PtO film is found to be 1–2 mΩcm and shows almost no temperature dependence. The metallic character of the PtO film is assumed to be suppressed by its poor crystallinity. The α-PtO 2 film has a large resistivity of approximately 1 Ωcm with a negative temperature coefficient, which indicates semiconducting characteristics. Thermal stability of PtO and α-PtO 2 films in air and in vacuum is studied. These films are stable up to 500°C and 250°C in air and in vacuum, respectively, and are reduced to Pt above these temperatures.