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

• High transmittance Ga-doped ZnO (GZO) thin films deposited by sol-gel process.
• At 4 at.% Ga doping level, the highest transmittance of 98.49% with minimum resistivity of 1.12 × 10− 2 Ω·cm was obtained.
• The optical band gap of GZO films increase with an increase in Ga content.

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 380–780 nm wavelength range. The PL spectra of the GZO films revealed a strong ultraviolet emission peaks at around 393 nm and a weak blue emission peak at around 468 nm. When the Ga doping level was 4 at.%, the minimum resistivity of 1.12 × 10− 2 Ω·cm with the highest transmittance was reached. The optical band gaps (Eg) of the films were increased from 3.311 eV to 3.329 eV with the increase of Ga dopant concentration.