Al-doped ZnO films deposited by reactive magnetron sputtering in mid-frequency mode with dual cathodes

Aluminum-doped zinc oxide (AZO) films were deposited on heated (300degreesC) glass substrates by reactive mid-frequency (mf, 50 kHz) magnetron sputtering using dual magnetron cathodes with aluminum-zinc alloy targets. In order to keep the very high deposition rate, reactive gas control using plasma emission was carried out to stabilize the discharge in the "transition region" of the reactive sputtering system. The highest deposition rate for the transparent conductive AZO films by this dual magnetron sputtering (DMS) system was 290 nm/min, which was higher than that for the conventional reactive sputtering system by one order of magnitude. The lowest resistivity of the AZO film was 3.9 x 10(-4) Omega cm. The structure and electrical properties of the films could be controlled systematically by the reactive gas control system in the transition region.