Joule heating simulations of VO₂ films

Vanadium dioxide (VO₂) undergoes an insulator-to-metal transition (IMT) when heated above 340 K. Recent studies have shown that an applied voltage can trigger the IMT, but it is still unclear whether the electric field or Joule heating drives the transition. To investigate the role of Joule heating in the voltage-triggered IMT, we used conductive atomic force microscopy (CAFM), which employs a biased tip in contact mode to measure the local current through a VO₂ film. Here we present a computational study of Joule heating in a VO₂ film due to CAFM bias sweeps. We use COMSOL Multiphysics, a finite element analysis software, to determine the local temperature and electric field prior to the IMT. This Joule heating model can reproduce the IV characteristics of the CAFM experimental data, confirming the importance of Joule heating in inducing the IMT. We extend our simulations to non-contact AFM dissipation measurements, in which the role of Joule heating in VO₂ is determined as a function of temperature and voltage, and the additional parameters of tip-sample distance and tip oscillation amplitude.