Nanocrystalline ZnO thin films by spin coating-pyrolysis method

The effect of polar solvent and Zn²⁺ molar concentration on structure and morphology of sol-gel derived ZnO thin films has been investigated. Zinc oxide thin films are fabricated by spin coating technique on p-Si (1 0 0) substrate using a homogeneous sol having polar and nonpolar composition. The thin films are obtained by pre-firing at 200 °C and subsequently annealing at higher temperatures. Phase and morphology analysis of the thin films is carried out by X-ray diffraction and field emission scanning electron microscopy respectively. Crystal orientation and pure phase evolution temperature of ZnO thin films was observed to be affected due to the presence polar solvent. The size of crystallites and thickness of the polycrystalline thin films were observed to be influenced by initial precursor concentrations. FTIR analysis suggested hydrolysis of zinc species in precursor sol. Optical property and material quality of the thin films were characterized by photoluminescence spectroscopy techniques. Strong UV luminescence along with negligible deep level emission was observed from the thin films.