Optical and dielectric properties of potassium-doped tin selenide polycrystals

Abstract

In our current study, we have investigated the effect of potassium doping on AC conductivity and the dielectric properties of tin selenide (SnSe). Potassiumdoped SnSe (K x Sn 1-x Se with x = 0-20 mol%) polycrystals were synthesized via hydrothermal method. The phase of the synthesized samples was confirmed to be single phase with orthorhombic structure as obtained by X-ray diffraction. The average crystallite size for all the K x Sn 1-x Se samples was calculated using the Debye-Scherrer formula and they were found to be decreased as potassium (K) concentration increased. Scanning electron microscope revealed plate-like morphology for all K x Sn 1-x Se samples. Transmission electron microscope studies at high resolution showed plate-like morphology which is connected with small nanorods for the K 0.20 Sn 0.80 Se. Optical studies were carried out using UV-Vis-NIR diffuse reflectance spectroscopy. The bandgap values were found to be decreased as K concentration is increased. Temperature-dependent dielectric studies were studied for all K x Sn 1-x Se samples. Correlated barrier hopping is responsible for the transport of charge carriers in the conduction mechanism. Electrical modulus studies reveal a non-Debye-type dielectric relaxation phenomenon. The results of dielectric studies specify the application of K-doped SnSe in frequency related and capacitive storage devices.