Highly Transparent and Conductive Zn2In2O5 Thin Films Prepared by RF Magnetron Sputtering

Abstract

A new transparent conducting Zn₂In₂O₅ film is demonstrated. The film was prepared by rf magnetron sputtering using binary compound targets composed of In₂O₃ and ZnO (with a Zn content (Zn/(Zn+In)) of 5-45 at%). The electrical properties were relatively independent of the substrate temperatures between room temperature and 350° C. A resistivity of 3.9×10^-4 Ω· cm and an average transmittance above 80% in the visible range were obtained for undoped Zn₂In₂O₅ films with a thickness of about 400 nm. The spatial resistivity distribution on the substrate surface was minimal for Zn₂In₂O₅ films. Optical measurements showed a band-gap energy of about 2.9 eV and a refractive index of about 2.4 for Zn₂In₂O₅. It was found that the resistance of the undoped Zn₂In₂O₅ films was more stable than that of undoped ZnO or In₂O₃ films in oxidizing environments at high temperatures.