Electrical conductivity and dielectric properties of cadmium thiogallate CdGa.sub.2S.sub.4 thin films

Cadmium thiogallate CdGa.sub.2S.sub.4 thin films were prepared using a conventional thermal evaporation technique. The dark electrical resistivity calculations were carried out at different elevated temperatures in the range 303-423 K and in thickness range 235-457 nm. The ac conductivity and dielectric properties of CdGa.sub.2S.sub.4 film with thickness 457 nm has been studied as a function of temperature in the range from 303 to 383 K and in frequency range from 174 Hz to 1.4 MHz. The experimental results indicate that [sigma].sub.ac([omega]) is proportional to [omega].sup.s and s ranges from 0.674 to 0.804. It was found that s increases by increasing temperature. The results obtained are discussed in terms of the non overlapping small polaron tunneling model. The dielectric constant ([epsilon]') and dielectric loss ([epsilon]") were found to be decreased by increasing frequency and increased by increasing temperature. The maximum barrier height (W.sub.m) was estimated from the analysis of the dielectric loss ([epsilon]") according to Giuntini's equation. Its value for the as-deposited films was found to be 0.294 eV.