Substrate temperature effect on the formation of PtRhO_x thin films

Conductive PtRhO_x thin films were deposited at various substrate temperatures on bare Si wafers by means of the reactive sputtering method, using a Pt₉Rh alloy target. (111)-axis oriented PtRhO_x thin films were obtained for a substrate temperature around 400 °C. From the X-ray photoelectron spectroscopy studies, the atomic ratio of oxygen to platinum, O/Pt, in PtRhO_x was found to decrease from 2.3 to 1.5 with increasing substrate temperature from 50 °C to 550 °C whereas the atomic ratio of Rh to Pt, Rh/Pt, remained constant at about 0.12. These results were attributed to a decrease of in the number of PtO₂ binding states, accompanied by an increase in the number of PrO binding states, with the number of Rh₂O₃ binding states remaining constant. The resistivity of PtRhO_x thin films deposited on Si wafers decreased to about 8.9×10^-5 Ωcm with increasing substrate temperature up to 650 °C.