High-rate reactive high-power impulse magnetron sputtering of transparent conductive Al-doped ZnO thin films prepared at ambient temperature

Reactive high-power impulse magnetron sputtering was used for high-rate (deposition rate of 60 nm/min) deposition of conductive (resistivity of 3 × 10−3 Ωcm) and optically transparent (extinction coefficient at the wavelength of 550 nm of 0.01) ZnO:Al thin films at ambient temperature (< 40 °C). We used planar Zn:Al target (3.09 at.% of Al) with diameter of 100 mm and thickness of 6 mm mounted on strongly unbalanced magnetron. The films were deposited in argon‑oxygen atmosphere at constant argon and oxygen partial pressure of 2.0 Pa and 0.1 Pa, respectively. An average target power and voltage pulse length were kept constant to 1.9 Wcm−2 and 200 μs, respectively. A pulse-averaged target power density was varied in the range of 190 Wcm−2–940 Wcm−2. Optical emission spectroscopy was used for better understanding of correlations between plasma discharge properties and structural, electrical and optical properties of prepared films.