Dielectric studies on Cd0.4Zn0.6Te thin films

The dielectric responses of Cd0.4Zn0.6Te thin films, deposited by the vacuum evaporation technique, were studied as a function of frequency and temperature for different substrate temperatures of the deposited films. Combined modulus and impedance plots were used to study the response of the film, which in general contains grains, grain boundaries, and the electrode/film interface as capacitive elements. The conductivity of the deposited films decreases with increase in substrate temperature. The dielectric constant varied between 15 and 6.8 for the films deposited in the range of substrate temperatures 300-473 K. The frequency analysis of the modulus and impedance studies showed the distribution of the relaxation times due to the presence of grains and grain boundaries in the films. The values of activation energies derived from the dissipation factor and modulus were found to be 0.64 and 0.61 eV, respectively for the films deposited at room temperature, which are higher than the values calculated from conductivity (0.41 eV). The deviation in these values was attributed to the energetic conditions of the grains and grain boundaries. (C) 2002 Elsevier Science B.V. All rights reserved.