W-doped vanadium dioxide films by pulsed laser deposition for IR Photonics

The semiconductor-to-metal phase transition exhibited by vanadium dioxide at the critical temperature of 68 °C, enables reversible changes in its optical and electrical properties. Moreover, the possibility to modify the transition temperature by introducing dopants within the VO2 crystal, allows a temperature tunability of all these properties, making this phase change material very appealing for active, dynamic, tunable Photonic applications. In this work we report on fabrication and structural, morphological, and optical characterization of tungsten (W)-doped VO2 thin films synthesized by pulsed laser deposition, a technique which allows a unique versatility to obtain W-doped VO2 films using custom made VO2 targets with different amounts of W. Results show that appropriate W-doping leads to VO2 thin films with tunable and controllable perfect IR absorption, paving the way to the development of promising thermooptical devices including infrared filters, radiative cooling devices, and thermal emitters. Furthermore, by varying the amount of W, tailored infrared phonon and plasmon polaritonic responses at room temperature can be obtained, allowing then the realization of VO2 films with a given degree of semiconducting/metallic behaviour, exploitable for the realization of tunable midinfrared metamaterial devices operating at room temperature.