Frequency and Temperature Dependent Capacitance of ε-GaSe Single Crystals: Evaluation of Its Negative Capacitance

Non-trivial capacitance behaviour of gallium selenide (ε-GaSe) single crystals has been discussed. The emphasis of our discussion is focussed to the physical mechanism and theoretical interpretation of experimentally observed data. The crystal used for this purpose was grown by vertical Bridgeman technique (VBT). The grown crystal belongs to ε- polytype (ε-GaSe) with hexagonal crystal structure. The functions of ε-GaSe single crystals as a dielectric medium have been studied by measuring the capacitance with varying frequency and temperature. The obtained results revealed that at a constant temperature, the value of capacitance decreases with frequency while, for a given frequency, the value of capacitance gradually increases with temperature. Capacitance measured at room temperature was found negative in higher regions of frequency: an unusual behaviour.