Effect of annealing and post-annealing in reducing atmosphere on the structural, optical and electrical properties of nanostructured ATZO thin films

Utilizing the sol–gel method, Al-Ti codoped ZnO (ATZO) thin films were deposited on glass substrates. The effects of annealing at different temperatures (500, 550 and 600 °C) and post annealing in reducing atmosphere on the structure, optical and electrical properties of the ATZO thin film were studied. The X-ray diffraction (XRD) analysis, field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) methods were used to investigate the structure, morphology and surface roughness of the thin films. The optical properties were investigated by UV–vis spectrophotometer. The XRD results show that increase in annealing temperature from 500 to 600 °C lead to increase in grain size from 19 to 31 nm. The obtained results of the XRD analysis were confirmed by the FE-SEM morphological characterization. The AFM measurements exhibit that the RMS roughness varies between 6.9–10.3 nm. It was concluded that the increase in the annealing temperature of the thin films up to 550 °C lead to improvement in the transparency and reduction of the resistivity. It was revealed that post annealing in a reducing atmosphere of 95% N2–5% H2 caused a significant reduction of the resistivity along with an increase in transmittance.