Structural, optical and dielectric properties of gadolinium incorporated laser ablated ZnO thin films

Gadolinium doped ZnO nanostructured thin films were prepared on quartz substrates by pulsed laser ablation. The effects of thermal annealing at temperatures 400 to 600 °C on the structural, optical and dielectric properties were investigated. The as deposited film is amorphous in nature and all the annealed films show polycrystalline nature with hexagonal wurtzite crystal structure. The AFM images of the doped films show a porous structure for the films. An enhanced transmittance and surface smoothness with increase in annealing temperature were observed. The band gap energy was increasing with decrease in particle size. The porosity and refractive indices of the films were calculated from the transmittance and reflectance spectra. The complex dielectric constant and the loss factor of the ZnO thin films were calculated. From the Photoluminescence spectra all the films show PL emission in the UV and visible region. The Oi type defects are responsible for the enhanced green emission.