Synthesis and properties of sol-gel derived transparent ZnO thin films: Effect of indium doping

High quality and transparent indium doped ZnO (IZO) thin films were deposited on glass substrates by sol-gel spin coating method. Zinc acetate and indium (III) chloride were used as precursor solution materials. Structural, morphological, and optical properties of the films were investigated as a function of indium doping ranging from 0.5% to 2.0 at % by X-ray diffraction, scanning electron microscopy, transmission and energy dispersive X-ray techniques. The films had polycrystalline nature and exhibited a hexagonal wurtzite structure with preferred c-axis orientation. The film surfaces exhibited uniform particle-like and granular morphologies. The optical transmittance spectra of the undoped ZnO and IZO films were taken in the wavelength ranging from 350-1000 nm. The transmittance IZO films compared to undoped ZnO has increased with increasing indium content. The chemical composition of the films indicated the presence of indium element in the ZnO films. These results make IZO thin films an attractive candidate for transparent material applications such as solar cells.