Multi-physics modeling of hysteresis in vanadium dioxide thin films

Vanadium dioxide (VO2) exhibits a strong metal-insulator transition (MIT) near 68°C. The resulting changes in electrical, optical, thermal and mechanical properties make VO2 thin films interesting for a variety of sensor and actuator applications. The transition displays significant hysteresis that may significantly affect device performance. An accurate model of the transition would be valuable for predicting and compensating these effects. In this paper we investigate first-principles, multi-physics models using simultaneous measurement of optical and electrical properties. Our experimental results strongly validate use of a standard Preisach model to capture hysteresis in the optical properties of the VO2 film. We then investigate several physics-based models relating electrical resistivity to the fraction of material transformed. Of the models investigated, a percolation-based approach is the most successful. There are opportunities for further refinement of the resistivity model and explicit treatment of temperature dependence.