Effect of Strain on Properties of Metal Doped VO₂ Based Thermal Sensors on Muscovite Substrate ^†

In this work, VO₂ based thermal sensing thin film synthesized on flexible muscovite substrates by direct oxidation of deposited vanadium metal, were investigated for the impact of doping and strain on their electrical properties. We investigated both undoped and Ti doped VO₂ on muscovite substrate and compared with those on Quartz substrate. Both doped and undoped VO₂ were found to undergo phase transition due to effect of heat as well as mechanical strain on muscovite substrate. On the other hand, the Ti doped VO₂, on both quartz and muscovite substrate showed significant reduction in the transition temperature compared to the undoped VO₂ thin films on these two substrates. When subjected to mechanical strain, the VO₂ thin film on muscovite substrates resulted in a decrease or an increase in resistance depending on whether the applied strain was tensile or compressive, respectively. The resistance change was also steeper around the transition temperature compared to room temperature, exhibiting high gauge factor. This metal doped VO₂ on flexible muscovite substrate has the significantly low transition temperature which causes the VO₂ film to undergo phase transition at a near-room temperature and enables it to be used as a temperature sensor with enhanced sensitivity.