Revealing the high sensitivity in the metal toinsulator transition properties of the pulsed laser deposited VO2 thin films

Manipulating the metal-to-insulator transitions of VO2 by combining compositing and doping strategies

“…20,22 Furthermore, the defects (e.g., grain boundary) within VO 2 can also cause a residual insulating phase that cannot completely transition to a metallic state across the T MIT . 19 Herein, we expected that compositing VO 2 with appropriate oxides with high resistivity should suppress charge leakage along the grain boundary of the VO 2 bulk pellets from the perspective of electrical transport. This would further improve the transition abruption of the MIT properties of the VO 2 bulk pellet, in addition to strengthening their mechanical properties due to compositing, as demonstrated recently.…”

“…It has previously been pointed out that the presence of grain boundaries may result in residual insulating VO 2 that cannot completely transit to the metallic state across the T MIT . 19,20 This situation can be altered by introducing a compositing phase within the grain boundary, which regulates carrier transport in both the insulating and metallic phases of VO 2 . To gain a better understanding, a two-phase model associated with the parallel connection of localized electrons (e.g., residual insulating VO 2 and compositing oxides) and itinerant electrons (e.g., metallic VO 2 ), was unitized for fitting the carrier transport of the metallic phase, as illustrated in Fig.…”

“…It has been previously recognized that the carrier transport and resulting MIT property of VO 2 are exceptionally susceptible to defects (e.g., grain boundary), as revealed by the polycrystalline VO 2 /quartz heterostructure. 19,20 Therefore, recognizing the potential impacts of the composite on the carrier transport and MIT properties of VO 2 bulk pellets is vital from the fundamental perspective.…”

Non-equilibrium Spark Plasma Reactive Doping Enables Highly Adjustable Metal-to-Insulator Transitions and Improved Mechanical Stability for VO2

“…For example, the MIT temperature ( T MIT ) that triggers the MIT is known to be rather sensitive to the valence state of vanadium that is at the intermediate valence state ( e.g. , V 4+ ) and susceptible to both oxidizing and reducing environments. − Conventionally, the MIT properties and electronic structure of VO 2 are adjusted by the elementary substitution, for example, the T MIT is elevated or reduced via substituting V 4+ by dopants with lower or higher valence states, respectively. , …”

“…Nevertheless, these applications of VO 2 are still challenged by its material synthesis as the electronic phase diagram of vanadium oxides is extraordinary complex 13 . For example, the metal to insulator transition temperature (T MIT ) that triggers the MIT is known to be rather sensitive to the valence state of vanadium that is at the intermediate valence state (e.g., V 4+ ) and susceptible to both oxidizing and reducing environment [14][15][16] . Conventionally, the MIT properties and electronic structure of VO 2 is adjusted by the elementary substitution, e.g., the T MIT is elevated or descended via substituting V 4+ by dopants with lower or higher valence states, respectively 17,18 .…”