Growth and characterization of high transmittance GZO films prepared by sol-gel method

Abstract

High transmittance Ga-doped ZnO thin films were deposited on glass substrates using sol-gel spin coating technique. Crystallinity levels, microstructures, optical and electrical properties of the thin films were systematically investigated by scanning electron microscope, X-ray diffractometer, UV–visible spectrophotometer, PL spectrometer and four-point probe method, respectively. All GZO thin films exhibited polycrystalline with a hexagonal wurtzite structure and slight (0 0 2) preferred orientation growth, which show excellent transmittance (>95%) in the 380–780nm wavelength range. The PL spectra of the GZO films revealed a strong ultraviolet emission peaks at around 393nm and a weak blue emission peak at around 468nm. When the Ga doping level was 4at.%, the minimum resistivity of 1.12×10−2Ω·cm with the highest transmittance was reached. The optical band gaps (Eg) of the films were increased from 3.311eV to 3.329eV with the increase of Ga dopant concentration.