Influence of Al Doping on the Properties of ZnO Thin Films Grown by Atomic Layer Deposition

Aluminum-doped zinc oxide (AZO) films were grown by atomic layer deposition at 200 °C. The influence of Al content on the structure, optical, and electrical properties of AZO films was investigated. The X-ray diffraction spectra revealed that the grown ZnAlO films have a hexagonal structure with a preferential c -axis orientation perpendicular to the substrate surface. Furthermore, a 0.1° peak shift at a diffraction angle of 34.5° from the wurtzite structure to higher values was observed after Al doping. The X-ray photoelectron spectra of AZO film showed that Zn exists only in the oxide states with an oxygen-deficient ZnO 1- x matrix. In photoluminescence studies, the intensity of the dominant peak at ∼380 nm was found to decrease with increasing Al doping concentration. In addition, a minimum resistivity of 9.36 × 10 –4 Ωcm was obtained for the AZO film with 2.7 at.% Al.