Dielectric relaxation and AC conductivity of XS (X = Cd, Zn) compounds

The dielectric properties of XS (X = Cd, Zn) compounds are studied by both capacitance and dissipation factor measurements in temperature range (303-523K) and frequency range (50Hz-5 MHz). A Debye-like relaxation of dielectric behavior has been observed (for US and ZnS compounds), which is found to be a thermally activated process with activation energies of 0.058 and 0.043 eV for US and ZnS compounds, respectively. Capacitance is found to decrease with increasing frequency, while it increases with increasing temperature. Obtained data of AC conductivity reveal that at low frequency sigma(AC)(omega) is independent of frequency and proportional to omega(s) at higher frequency for the two compounds. The values of the frequency exponent, s, were found to decrease by increasing temperature. This suggests that the Correlated Barrier Hopping (CBH) model is the operating mechanism. Finally, the maximum barrier height W-M and the density of states N(E-F) through the two compounds were determined. (c) 2005 Elsevier B.V. All rights reserved.