Structural, Optical and Dielectric Properties of Sn-doped ZnO thin Films: Effect of Doping Concentration

The role of Sn doping concentration on structural, optical and dielectric properties of ZnO:Sn thin films are examined. The films are prepared by successive ionic layer adsorption and reaction method. The XRD pattern reveals the Wurtzite geometry of undoped and Sn-doped ZnO thin films. The dopant enhances the z-axis orientation of the prepared films. The crystallite size and the periodicity of atoms are decreased due to doping. The unit cell parameters, bond length and Young's modulus are examined. The undoped ZnO film has a band gap of 3.17 eV whereas the red-shifted band gap is observed when doping is done. The films show higher hole concentration than electron concentration and hence the films are positive-type. The enhanced charger carrier concentrations are observed at high doping concentrations. The UV and violet emission are observed in the photoluminescence spectrum and the quenching is observed due to doping. The dielectric properties such as impedance, reactance, phase angle and loss coefficient are discussed as a function of Sn doping concentration.