Physical properties of Gd doped ZnO thin films grown by spray pyrolysis

Undoped ZnO, Gd doped ZnO (GZO) thin films were prepared by chemical spray pyrolysis method at 350°C on glass substrates. The effect of gadolinium doping on structural, morphological, optical and electrical properties as function of dopant concentration has been studied. X-ray analysis showed that the films are polycrystalline fitting well with hexagonal wurtzite structure and have preferred orientation in [002] direction. The AFM analysis showed that the grain size as well as the roughness of the Gd doped ZnO films constantly decreases with increasing dopant content. The deposited films showed an average optical transmittance around 85% in the visible region and the optical band gap of the ZnO:Gd films decreases from 3.27 eV to 3.18 eV as dopant content increases. Hall Effect measurements showed that electrical conductivity, mobility carriers and carrier concentration of the films are increased after 1.5 % Gd doping concentration.