Optical properties and constants of Ga-doped ZnO thin films grown on muscovite mica substrates for optoelectronic applications

Ga-doped ZnO (GZO) thin films were grown on muscovite mica substrates by sol-gel spin-coating. The effects of post-annealing on the optical properties and constants of the GZO thin films were investigated. All the films exhibited strong near-band-edge emission in the UV range, while the defect-related deep-level emission in the visible region was only observed at 600 degrees C. The average transmittance of the films was about 75% in the visible region and the sharp absorption edges were shifted toward a higher wavelength and became sharper with an increase in the post-annealing temperature. The refractive index was measured for the as-grown and annealed GZO thin film at 500 degrees C . The single oscillator energy, dispersion energy, M-1 and M-3 moments, average oscillator strength and wavelength, and the refractive index at an infinite wavelength were obtained from the refractive index values of the films. In addition, the real and imaginary parts of the dielectric constant and optical conductivity of the films were measured.