Structural and optical properties of nitrogen-doped zinc oxide thin films grown on muscovite mica substrates using Sol-Gel process

Nitrogen (N)-doped zinc oxide (NZO) thin films were grown on muscovite mica substrates by sol–gel spin-coating and their structural and optical properties were investigated for various N concentrations (0, 3, 6, 9, and 12 at. %). The surface morphologies of all the films exhibited granular structures consisting of spherical nano-sized crystallites. The (1 0 0) and (0 0 2) diffraction peaks were observed at 0, 3, and 6 at. % N concentration, while the (1 0 0) peak could not be distinguished and the (0 0 2) peak intensities decreased gradually at the higher concentrations. The near-band-edge to deep-level emission intensity ratio increased significantly with increasing N concentration up to 6 at. %. All the films exhibited an average transmittance of more than 75% in the visible region. The optical band gap and Urbach energy determined by the measured transmittance were obviously dependent on the N concentration