Impedance Spectroscopy of Nano-Grain ZnO Thin Films

Abstract

ZnO thin films of various thicknesses were prepared by metal organic chemical vapor deposition technique. The structural and micro structural characteristics of the grown films are studied using XRD and FESEM respectively. The film thickness is estimated from the cross sectional micrographs and is also verified using filmetrics studies. The electrical response of all the nano-grain ZnO thin films was studied using impedance spectroscopic technique. The circuit parameters were determined using an equivalent circuit model presuming both the grain and grain boundary contributions to the conductivity. The variation in conductivity of thin films with their thicknesses was attributed to the microstructure of the thin films and traping of oxygen vacancies on the surface of the film.