Sputter deposited Pt–Ir oxides thin films and their characterization

Pt–Ir and their oxides mixture thin films were prepared on Si(1 0 0) substrates at temperatures 500 and 600 °C by reactive rf magnetron sputtering with Pt–20 mass% Ir target and Ir chips set on the target. X-ray fluorescence analysis revealed that deposited films had a composition from Pt–20 mass% Ir to Pt–60 mass% Ir. Further Increase in Ir contents in the films resulted in a delamination of films from Si substrate. Deposition atmosphere was varied with O2/Ar flow ratio from 0 to 20%. Deposited films consisted of Pt–Ir alloy and their oxides such as PtO, PtO2 and IrO2, which were characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electric resistivity of the films was measured to be from the order of 10−4 to 10−3 Ω cm by dc four probe method. In order to study performance of the films as electrode, SrTiO3 as dielectrics and Pt as upper electrode were sputter deposited on Pt–Ir oxide/Si substrates in order. And current/voltage characteristics of SrTiO3 were measured. Leakage current density of SrTiO3 with 200 nm in thickness deposited on Pt–50 mass% Ir oxide electrodes and on Pt–50 mass% Ir alloy electrode were 1.7×10−7 and 1.0×10−6 A/cm2 at 2.0 V of applied voltage, respectively. SrTiO3 with100 nm in thickness, however, showed poor current/voltage characteristics.