Effects of substrate temperature on properties of ITO–ZnO composition spread films fabricated by combinatorial RF magnetron sputtering

We have fabricated ITO–ZnO composition spread films to investigate the effects of substrate temperature on their electrical and optical properties by using combinatorial RF magnetron sputtering. It turned out by X-ray measurement that the film with zinc contents above 16.0 at% [Zn/(In+Zn+Sn)] showed amorphous phase regardless of substrate temperature. The amorphous ITO–ZnO film had lower resistivity than polycrystalline films. When the films were deposited at 250 °C, the minimum resistivity of 3.0×10 −4 Ω cm was obtained with the zinc contents of 16.0 at%. The indium content could be reduced as high as ~30 at% compared to that of ITO for the films having similar resistivity (~10 −4 Ω cm). However, a drastic increase of resistivity was observed for the ITO–ZnO films deposited at 350 °C, having zinc contents below 15.2 at%. The effects of substrate temperature on properties of ITO–ZnO films were investigated by using combinatorial RF magnetron sputtering. The amorphous ITO–ZnO film had lower resistivity than polycrystalline films. The minimum resistivity of 3.0×10 −4 Ω cm was obtained with the substrate temperature of 250 °C and the zinc contents of 16.0 at%. The electronic states of ITO–ZnO films were discussed with related to the formation of transparent amorphous oxide semiconductor (TAOS).