This research investigates the influence of annealing temperature on the structural, morphological, optical, and electrical properties of Al doped ZnO thin films synthesized using a cost-effective sol–gel spin coating technique. The films were annealed at temperatures ranging from 100°C to 500°C to evaluate temperature-dependent modifications in material behavior and performance. X-ray diffraction (XRD) analysis confirmed the hexagonal wurtzite crystal structure of ZnO, with a notable enhancement in crystallinity and grain orientation at elevated annealing temperatures. Field emission scanning electron microscopy (FESEM) revealed distinct morphological transitions from loosely aggregated nanoparticles to well-defined crystalline grains as the annealing temperature increased. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) further validated the successful incorporation of Al into the ZnO lattice and the preservation of the ZnO structure. Optical absorption measurements exhibited a red shift in the absorption edge with rising temperature, resulting in a reduction of the optical band gap from 3.16 eV to 2.96 eV. Photocurrent analysis demonstrated a significant improvement in photoresponse for highly annealed samples, attributed to enhanced crystallinity and optimized surface morphology. Additionally, a consistent decrease in electrical resistivity with increasing annealing temperature indicates improved carrier transport. Overall, the study highlights the critical role of annealing temperature in tailoring the functional properties of Al-doped ZnO thin films for advanced optoelectronic applications.
More et al. (Mon,) studied this question.