Low temperature formation of textured ZnO transparent electrodes by magnetron sputtering

This article describes a high pressure magnetron sputtering technique that results in milky transparent conducting Al-doped ZnO (ZnO:Al) films with a textured surface prepared on substrates at a temperature of 200 °C. Large-area milky transparent conducting ZnO:Al films with a uniform spatial resistivity distribution on the substrate were prepared at a sputter pressure of 60–80 Pa by direct current magnetron sputtering. A total transmittance of 72% and a haze factor of 54% at a wavelength of 550 nm as well as a sheet resistance as low as 16 Ω/sq were obtained in milky ZnO:Al films of about 1000 nm thick prepared at a sputter pressure of 80 Pa. In addition, a two step deposition that realizes a high deposition rate and a low sheet resistance was demonstrated. A 1350-nm-thick milky ZnO:Al film with a sheet resistance of 4 Ω/sq and a haze ratio of 13% at a wavelength of 550 nm was prepared that had about a five times greater deposition rate than that observed at a high sputter pressure of 80 Pa.