In this work, zinc oxide (ZnO) thin films are deposited on glass substrate using the sol-gel spin coating technique. The effect of annealing temperature on structural properties was investigated. The ZnO sol-gel was produced from zinc acetate dehydrate as the starting material with iso-propanol alcohol as the stabilizer. The ratio was controlled, distilled water and diethanolamine as the solvent mixing on a magnetic stirrer for an hour under constant heat of 60°C. The ZnO thin film was deposited using the spin coating technique with the speed of 3000 rpm for 30 minutes before the sample undergoes pre-heat in the oven at the temperature of 100°C for 10 minutes. The sample was annealing in the furnace for an hour at 200°C, 350°C, and 500°C. The X-ray diffraction (XRD) analysis confirms that hexagonal wurtzite structure with zincite and zinc acetate hydroxide hydrate composition. The thin films surface roughness was analyzed using an atomic force microscope (AFM) and scanning electron microscope (SEM) for surface morphology observation.

Zinc oxide (ZnO) is a prominent n-type semiconductor material used in optoelectronic devices owing to the wide bandgap and transparency. The low-temperature growth of ZnO thin films expands diverse applications, such as growth on glass and organic materials, and it is also cost effective. However, the optical and electrical properties of ZnO films grown at low temperatures may be inferior owing to their low crystallinity and impurities. In this study, ZnO thin films were prepared by atomic layer deposition on SiO2 and glass substrates in the temperature range of 46-141℃. All films had a hexagonal würtzite structure. The carrier concentration and electrical conductivity were also investigated. The low-temperature grown films showed similar carrier concentration (a few 1019 cm−3 at 141°C), but possessed lower electrical conductivity compared to high-temperature (>200°C) grown films. The optical transmittance of 20 nm thin ZnO film reached approximately 90% under visible light irradiation. Additionally, bandgap energies in the range of 3.23-3.28 eV were determined from the Tauc plot. Overall, the optical properties were comparable to those of ZnO films grown at high temperature.