Abrupt metal-insulator transition observed in VO2 thin films induced by a switching voltage pulse

TL;DR

This study demonstrates an abrupt, fast metal-insulator transition in VO2 thin films triggered by a voltage pulse, with potential switching times under a nanosecond, highlighting the role of electron correlations.

Contribution

It reports the observation of an ultrafast, voltage-induced MIT in VO2 films and analyzes the transition dynamics, suggesting intrinsic switching times below one nanosecond.

Findings

Switching voltage threshold is 7.1 V.

Switching time can be as low as 9 ns.

Intrinsic switching time is estimated to be less than 1 ns.

Abstract

An abrupt metal-insulator transition (MIT) was observed in VO2 thin films during the application of a switching voltage pulse to two-terminal devices. Any switching pulse over a threshold voltage for the MIT of 7.1 V enabled the device material to transform efficiently from an insulator to a metal. The characteristics of the transformation were analyzed by considering both the delay time and rise time of the measured current response. The extrapolated switching time of the MIT decreased down to 9 ns as the external load resistance decreased to zero. Observation of the intrinsic switching time of the MIT in the correlated oxide films is impossible because of the inhomogeneity of the material; both the metallic state and an insulating state co-exist in the measurement volume. This indicates that the intrinsic switching time is in the order of less than a nanosecond. The high switching speed might arise from a strong correlation effect (Coulomb repulsion) between the electrons in the material.