Dielectric and electric modulus properties of vacuum evaporated Cd0.8Zn0.2Te thin films

Cd0.8Zn0.2Te thin films were prepared by vacuum evaporation technique. The variation of dielectric constant and dielectric loss tangent were found to depend on temperature and frequency. Impedance and electric modulus formalisms were employed in order to gain an insight into the microstructural details of films. A comprehensive study on the relaxation mechanism revealed that the presence of grain and grain boundaries across the film thickness were the basic relaxation phenomenon. The activation energies calculated from the loss tangent and spectroscopic modulus mechanism were found to vary between 1.24 and 0.91 eV for the film of thicknesses 230-800 nm. The frequency analysis of modulus properties showed a distribution of relaxation times. Conductivity plots against frequency at higher frequency suggested the response obeying the universal power law. The role of bulk and grain boundary in the overall conduction process has been discussed with realistic justification. The defect density varies between 2 and 5x1015 eV-1 m-2 for the films of thicknesses studied