Anomalous optical switching and thermal hysteresis behaviors of VO2 films on glass substrate

In order to study the optical switching of vanadium dioxide (VO2) and its thermal hysteresis behavior, we fabricated VO2 films on glass substrates at various oxygen pressures. Only the VO2 films made at 5–10 mTorr displayed x-ray diffraction peaks and metal-insulator transition. Upon heating and cooling, remarkably, these samples exhibited significant optical switching behaviors with a clockwise thermal hysteresis in the infrared range of >850 nm or with a counterclockwise thermal hysteresis in the near visible range of 650–850 nm. The temperature dependence of optical absorption was explained by the O2p-V3d splitting depending on the structural transition of VO2.