Transparent metal oxide films based sensors for solar tracking applications

Titanium dioxide:zinc oxide (TiO2:ZnO) composite thin films were prepared onto glass and p-type silicon substrates by the sol–gel spin coating technique. The composite metal oxide films indicate a high transmittance more than 90% in visible region. Optical constants such as optical band gap and refractive index of the films were determined using transmittance and reflectance spectra. TiO2:ZnO/p-Si diodes exhibited a high photocurrent responsivity under various solar illuminations. Electronic parameters like ideality factor, series resistance and barrier height were determined from I–V characteristic curves, Cheung model and Norde equations. The capacitance–voltage and conductance–voltage of the diodes were measured in the range from 10 kHz to 1 MHz. The capacitance of the diodes exhibited a decrease in capacitance and increase in conductance with increasing frequency. The obtained results suggest that TiO2:ZnO/p-Si diodes can be used as a sensor in optic communications and optoelectronic applications.