Transparent conductive Al-doped ZnO thin films grown at room temperature

Abstract

Aluminum-doped ZnO (ZnO:Al, AZO) thin films were prepared on glass substrates by dc reactive magnetron sputtering from a Zn–Al alloy target at room temperature. The effects of the Ar-to-O2 partial pressure ratios on the structural, electrical, and optical properties of AZO films were studied in detail. AZO films grown using 100:4 to 100:8 Ar-to-O2 ratio result in acceptable quality films with c-axis orientated crystals, uniform grains, 10−3 Ω cm resistivity, greater than 1020 cm−3 electron concentration, and high transmittance, 90%, in the visible region. The lowest resistivity of 4.11×10−3 Ω cm was obtained under the Ar-to-O2 partial pressure ratio of 100:4. A relatively strong UV emission at ∼3.26 eV was observed in the room-temperature photoluminescence spectrum. X-ray photoelectron spectroscopy analysis confirmed that Al was introduced into ZnO and substitutes for Zn and doped the film n-type.