Abstract
•Novel dielectric and electrical performances of the ε-GaSe single crystals.•Nontrivial observation of negative dielectric constant (NDC) in ε-GaSe dielectric.•Physical mechanism and theoretical interpretation of observed NDC.•Remarkable phase shift in the circuit behavior from inductive to capacitive at 325 K.
The frequency and temperature dependence of ac conductivity in a ε-GaSe single crystal was studied by assessing the dielectric constant (εr) and loss tangent (tanδ) over a broad frequency range. GaSe as a dielectric exhibited the typical effect of negative dielectric constant (NDC) at room temperature. A possible mechanism for understanding the reason behind the presence of NDC has been demonstrated on the basis of Drude model. In addition, the crystal as a dielectric material portrayed a remarkable shiftin the εr value from negative to positive at an increase of ~25 oc from room temperature. This clearly demonstrates the phase shift in the circuit behaviour from inductive to capacitive. Overall, the value of εr, tanδ, and σac was found to increase with temperature and frequency. This is primarily a result of the impact of space charge polarization, and frequency power law (σac∝ωn). The presented result thus advocates that the as grown ε-GaSe single crystal could be used as a smart and efficient dielectric material in electronic devices.