Optical band gap and photoluminescence studies of precursor optimized Indium-Gallium Zinc oxide thin films

Abstract

Spray pyrolysis at an optimal substrate temperature of 400 °C produces thin layers of pure and Indium-Gallium doped Zinc oxide on glass substrates. In the growth of precursor solution, ammonium acetate is used as a stabilizing agent. Polycrystalline films with hexagonal shaped crystalline structures are deposited in all cases. We have investigated the optical band gap and photoluminescence behavior of Indium and Gallium doped Zinc oxide thin films. Powder X-ray diffraction studies show that the deposited thin films are polycrystalline structure, with a hexagonal crystal structure with (002) orientation. In the visible wavelength range, all thin films have a transmittance of around 85% and a strong absorption beginning of about 375 nm, which corresponds to the fundamental absorption edge of 3.3 eV of Indium-Gallium doped ZnO. UV–Vis-NIR results along with tauc’s plot show that energy gap decreases with the increase of Indium-Gallium doping concentration. Photoluminescence results indicate the effect of indium-gallium dopants at of various concentrations plays a significant role in the defect chemistry in the films.