Investigation of structural, optical and dielectric properties of the zinc oxide thin films

ZnO thin films were synthesised using the sol-gel spin-coating method. Zinc acetate dihydrate was used as the precursor, 2-methoxyethanol as the solvent, and di-ethanolamine as a stabiliser. The solution was deposited on glass substrates using a spin coater at rotation speeds of 1000, 2000, and 3000 rpm, preheated at 180°C on a hot plate for 1 h, and annealed at 400°C in a furnace for 4 h. To investigate the properties of ZnO thin films, the effects of spin speeds on the structural, optical, and dielectric properties of the deposited layers were investigated. XRD analysis revealed that all films possess a polycrystalline hexagonal wurtzite structure with a dominant (101) orientation, consistent with the standard JCPDS reference data. Atomic force microscopy and scanning electron microscopy revealed a granular surface morphology with pronounced valley-like features. UV-Vis spectroscopy results showed that optical transmission increases with increasing wavelength in the region between 300 and 900 nm. The dielectric studies demonstrated a high dielectric constant at low frequencies, which decreased with increasing frequency. These results indicate the potential of ZnO thin films may be promising for applications in solar cells, piezoelectric devices, and electrode materials.