Size‐Dependent Insulator‐to‐Metal and Metal‐to‐Insulator Phase Transitions in VO2 Microrods Grown on a Silicon Substrate

Abstract

Light scattering from VO2 microrods (MRs) synthesized on a silicon substrate is studied as a function of temperature and wavelength through the insulator‐to‐metal (IMT) and the metal‐to‐insulator (MIT) transitions. Light scattering exhibits substantial and reproducible changes. By focusing the light on individual MRs, it is shown that for small‐sized MRs (<1 × 10 μm), the IMT and MIT are very sharp with transition temperatures varying within 31–64 °C (IMT) and within 58–76 °C (MIT). In contrast, for large‐sized MRs (≈4 × 40 μm), only the IMT at 68 °C is sharp, whereas MIT is stretched with a prominent low‐temperature shoulder at 35–50 °C. The observed phenomena are assumed to be connected with the external substrate‐induced mechanical stress emerging during the phase transition. A simple model is developed to explain both the temperature‐stretched MIT and the low‐temperature shoulder.