Investigation of structural and optical parameters of yttrium-doped ZnO thin films prepared via spin coating of simple aqueous solution

Water-induced solution processing has gained interest for being environmental friendly. In this study, yttrium(Y)-doped ZnO thin films (ZnO:Y) on glass substrates using water-induced deposition route, without incorporating with sol-gel technique, were fabricated. The Y concentration as a dopant was varied as (0, 0.031, 0.047 and 0.063) atomic (at) % in the synthesized films. The morphological, structural and optical properties of these films were investigated using atomic force microscopy (AFM), Raman spectroscopy and spectroscopic ellipsometry. AFM investigations found out that all films are free of cracks and morphology changed significantly with doping. This low-cost deposition route has produced the wurtzite phase of ZnO in all thin films and Y-doping has improved the crystallinity. The films were highly transparent with transmission coefficient above 80% and an increase in the bandgap energy from 3.15 to 3.27 eV, with Y-doping, was observed. The optical constants such as refractive index, extinction coefficient and dielectric constants were extracted from SE results. The present study demonstrated that simple water-based solution processing is robust and can produce high-quality ZnO thin films for use in large-scale electronic and optical applications.