Room-temperature deposition of InOx films for transparent electronics by long-throw magnetron sputtering

Transparent undoped semiconductor indium oxide films were deposited long-throw rf magnetron sputtering at room temperature. It was experimentally verified that the variation of oxygen content in sputtering gas has a strong influence on the structural and electrical properties of the films. Results show that electrical resistivity variation of 3.5× 10^-2 to 4.7× 10⁴ Ω-cm for films produced at oxygen contents ranging from 0 to 50 % was obtained, and structural measurements show that films are polycrystalline. The optical band gap decreases as the oxygen content in the sputtering gas increases and the average visible transmittance is ~85%. Transparent TFTs present threshold voltages near 1.5 V and on/off ratios of 2.2×10⁷.