Tuning of the electrical and thermal properties of SnSb2S4 sulfosalt vacuum evaporated thin films subjected to a heat treatment for thermoelectric application

Abstract

This work covers the results of annealing effect in air on the structural, electrical and thermal properties of SnSb2S4. These films were deposited on unheated glass substrates by vacuum thermal evaporation and then they were subjected to annealing process for one hour in air ambient at 300 °C. First, X-ray diffraction analysis revealed that annealed film corresponds to SnSb2S4 material which has polycrystalline nature and the cristallites have the preferential orientation towards 531 direction. Second, the electrical properties have been investigated by means of complex impedance spectroscopy technique in frequency range 40 Hz–107 Hz and in temperature range 300 K–540 K. The effect of frequency and temperature on dielectric constant and dielectric loss has been discussed in terms of hopping of charge carriers. Moreover, the activation energy was estimated from both temperature dependence of dc conductivity and relaxation time data. Finally, the electro-pyroelectric method has been recognized as a reliable and useful tool for the measurement of thermal properties of SnSb2S4. Using a new approach based on theoretical models of electro-pyroelectric method, thermal properties of SnSb2S4 have been deduced. Indeed, thermal conductivity of annealed film at 300 °C is about 80.4 Wm−1 K−1. These results may be of interest for thermoelectric application of such ternary material.