Effect of Ga doping on the structural, optical, and electrical properties of ZnO nanopowders elaborated by sol-gel method

Nanostructured ZnO has received a considerable amount of interest, owing to its unique physical and chemical characteristics, as well as its remarkable performance in the fields of electronics, optics, and photonics. This work aims to study the influence of Ga dopant on the structural, optical, and electrical properties of ZnO nanopowders. Undoped and Ga-doped ZnO (GZO) nanopowders were successfully synthesised with the soft chemical sol-gel method. The solution was prepared using zinc acetate dihydrate and gallium (III) nitrate hydrate as precursors. The ethylene glycol is used as solvent. The X-ray diffractometer, scanning electronic microscope (SEM), UV-Vis, FTIR, and four-point probe method are used to analyse the properties of the synthesised powders. XRD and FTIR measurements show the growth of pure and Ga-doped ZnO crystals, which have a hexagonal wurtzite structure, and the average crystallite size varies from 9.09 nm to 24.8 nm. The nanospherical morphology of the nanopowders synthesised can be seen in the SEM images. The UV-visible spectroscopy shows that the optical gap energy increases with Ga concentration, from 3.59 eV to 3.67 eV. The I-V electrical measurements indicate that the breakdown voltage and the non-linear coefficient increase with Ga doping. This study will open the way for the investigation of a relationship between the electrical and nanostructural features of ZnO-based varistors for future device applications.