Anomalous large electrical capacitance of planar microstructures with vanadium dioxide films near the insulator-metal phase transition

Abstract

The temperature dependence of electrical capacitance of planar microstructures with vanadium dioxide (VO2) film near the insulator-metal phase transition has been investigated at the frequency of 1 MHz. Electrical capacitance measurements of the microstructures were performed by the technique based on the using of a two-terminal resistor-capacitor module simulating the VO2 layer behavior at the insulator-metal phase transition. At temperatures 325–342 K, the anomalous increase in microstructures capacitance was observed. Calculation of electric field in the microstructure showed that VO2 relative permittivity (ε) reaches ∼108 at the percolation threshold. The high value of ε can be explained by the fractal nature of the interface between metal and insulator clusters formed near the insulator-metal phase transition.