ZAO: an attractive potential substitute for ITO in flat display panels

Al-doped ZnO (ZAO) is an attractive material, as it is cheap and abundant, it is nontoxic, has comparable electrical, optical and infrared (IR) properties to ITO, is cost-effective and is easy to fabricate. In this paper, ZAO films have been prepared by reactive magnetron sputtering. Their electrical conductivity is shown to be in the region of 10−4 Ω cm. The influence of the substrate-to-target distance and deposition temperature on the resistivity of ZAO films has been studied. Their IR and optical properties have been investigated with UV–VIS and Fourier transformation IR spectrometry. It was shown that the visible transmittance and IR reflectance of ZAO films deposited on polyester at room temperature are comparable to those of ITO films. ZAO films have n-type conductivity. It was found that by adding Al to ZnO the variation in resistivity of ZAO films was decreased, and was usually no more than 1% at 50–400°C in vacuum and 5% at 50–400°C in air.