As a strongly correlated metal oxide, VO₂ inspires several highly technological applications. The challenging reliable wafer-scale synthesis of high quality polycrystalline VO₂ coatings is demonstrated on 4” Si taking advantage of the oxidative sintering of chemically vapor deposited VO₂ films. This approach results in films with a semiconductor-metal transition (SMT) quality approaching that of the epitaxial counterpart. SMT occurs with an abrupt electrical resistivity change exceeding three orders of magnitude with a narrow hysteresis width. Spatially resolved infrared and Raman analyses evidence the self-assembly of VO₂ disordered metamaterial, compresing monoclinic (M1 and M2) and rutile (R) domains, at the transition temperature region. The M2 mediation of the M1-R transition is spatially confined and related to the localized strain-stabilization of the M2 phase. The presence of the M2 phase is supposed to play a role as a minor semiconducting phase far above the SMT temperature. In terms of application, we show that the VO₂ disordered self-assembly of M and R phases is highly stable and can be thermally triggered with high precision using short heating or cooling pulses with adjusted strengths. Such a control enables an accurate and tunable thermal control of the electrical switching.

Tunable materials are paving the way towards improved functionality of metamaterials. Vanadium oxide (VO2) with its prototypical near-room-temperature transition between phases featuring greatly contrasting electrical and optical behavior is an appealing candidate as an active component in metamaterials. However, it is seldom known that VO2 in itself has metamaterial characteristics. VO2 under certain temperature conditions demonstrates a phase coexistence enabling highly tunable electrical and optical properties. In this chapter, we describe how VO2 in its hysteretic region behaves as a smart responsive Metasurface with cutting edge applications.