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 degrees 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 degrees peak shift at a diffraction angle of 34.5 degrees 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 ZnO1-x matrix. In photoluminescence studies, the intensity of the dominant peak at similar to 380 nm was found to decrease with increasing Al doping concentration. In addition, a minimum resistivity of 9.36 x 10(-4) Omega cm was obtained for the AZO film with 2.7 at.% Al.