Observation of the voltage-triggered insulator to metal transition in a VO₂ thin film as a function of temperature.

VO₂ undergoes an insulator to metal transition with a resistivity change up to five orders of magnitude upon heating through 340 K. The transition has also been observed via current-voltage (IV) measurements as a sharp jump in the current when sweeping the applied voltage. We have previously used the tip of an atomic force microscope (AFM) to map the local current response of voltage-biased polycrystalline VO₂ thin films[1]. We have fit the IV curve immediately preceding the transition to the temperature-dependent Poole-Frenkel conduction mechanism and calculated the local temperature of the film. While these measurements were nominally performed at room temperature, we calculated an increased local temperature of 335 K immediately preceding the transition, confirming the role of Joule heating in our voltage-biased, tip-sample geometry. Here, we extend these measurements to a wider temperature range to further understand the effects of Joule heating on the voltage-triggered insulator to metal transition in VO₂ thin films. ([1] Spitzig et al. arXiv:1903.03062v1)