UV-irradiated sol-gel spin coated AZO thin films: enhanced optoelectronic properties

Thin films of transparent conductive Al doped ZnO (AZO) thin films were produced via sol-gel spin coating route. Structural, optical, and electrical properties were explored for several dopant concentrations. Formation of crystalline AZO was verified by X-ray Diffraction (XRD) Analysis and structural analysis were carried out later from the XRD data. Highest band gap of 3.67 eV was found for 2 mol % AZO thin films. The average transmittance was found to be 84.19% in the visible spectra for the corresponding thin films. 2 mol% AZO also exhibited a minimum resistivity of 2.05 Ω-cm with a maximum value of figure of merit. Prolonged UV irradiation was applied to 2 mol % AZO thin films prior to annealing. It significantly modified the surface morphology of the film and provided shielding near UVA (315-378 nm) spectrum. This also enhanced the conductivity of the thin film by 3-fold compared to non-UV treated sample and decreased optical band gap significantly.