Admittance and photoadmittance spectroscopy of zinc oxide layers grown on p-Si substrates by sol-gel and spin coating method

In this work, the dielectric response of ZnO thin films has been studied over a temperature range of 200 K – 550 K. The dielectric response of polycrystalline ZnO thin films in the frequency domain was measured from 0.1 Hz - to 5 MHz frequencies with a small AC signal amplitude at different temperatures. Influence of the light on conductivity has been also investigated. A universal power law relation was brought into picture to explain the frequency dependence of AC conductivity. The temperature dependence of AC conductivity was analyzed in detail. The activation energy obtained from the temperature dependence of AC conductivity was attributed to the shallow trap-controlled space charge conduction in the bulk of the sample.