Complex ac conductivity of tellurium cuprate glassy semiconductors

Abstract

The frequency and temperature dependence of the real and imaginary parts of the ac conductivity of the tellurium cuprate glassy semiconductors are reported in the frequency range 10²-10⁵ Hz and in the temperature range 80-350 K. The experimental data have been analyzed with reference to various theoretical models based on quantum-mechanical tunneling of electrons or polarons through the barrier separating localized states, and on classical hopping of the same charge carriers over a similar barrier. The analysis indicates that the classical correlated-barrier hopping model of single electron is the most appropriate to describe the observed data. This model quantitatively predicts the temperature dependence of the ac conductivity and its frequency exponent for the measured temperature range. The physical parameters obtained by fitting the experimental results to this model are consistent with glass compositions.