Field Effect and Strongly Localized Carriers in the Metal-Insulator Transition MaterialVO2

Abstract

The intrinsic field effect, the change in surface conductance with an applied transverse electric field, of prototypal strongly correlated VO(2) has remained elusive. Here we report its measurement enabled by epitaxial VO(2) and atomic layer deposited high-κ dielectrics. Oxygen migration, joule heating, and the linked field-induced phase transition are precluded. The field effect can be understood in terms of field-induced carriers with densities up to ∼5×10(13) cm(-2) which are trongly localized, as shown by their low, thermally activated mobility (∼1×10(-3) cm(2)/V s at 300 K). These carriers show behavior consistent with that of Holstein polarons and strongly impact the (opto)electronics of VO(2).

Facet‐Dependent Phase Control by Band Filling and Anisotropic Electron–Lattice Coupling in HVO2 Epitaxial Films

“…[1,2] Use of carrier doping to control the electron correlation can move the system away from the integer numbers of d band filling and upset their stability, and thus causes phase transition from localized correlated insulator to itinerant correlated metal. [2] To date, chemi cal doping (i.e., chemical substitution of aliovalent cation [5,6] ) or electrostatic doping (i.e., dielectric [7] or ionic liquid gating [8,9] ) has been mainly used to inject carriers into correlated electron systems. [2] To date, chemi cal doping (i.e., chemical substitution of aliovalent cation [5,6] ) or electrostatic doping (i.e., dielectric [7] or ionic liquid gating [8,9] ) has been mainly used to inject carriers into correlated electron systems.…”

Switching VO2 Single Crystals and Related Phenomena: Sliding Domains and Crack Formation

“…To emphasize the importance of VO 2 and its potential applications, the reader is directed to a rather incomplete collection of recent articles that address this topic [4,5,6,7,8,9,10,11]. Here we focus on the I–M domain structure in the mixed state of VO 2 crystals during switching and to the damage caused by the structural changes [12]—both visible under the microscope due to the optical changes [13].…”

Interplay Between Extra Charge Injection and Lattice Evolution in VO2/CH3NH3PbI3 Heterostructure

“…On the other hand, only one V–V distance of 2.85 Å exists in the high‐temperature rutile phase shown in the lower trace of Figure b. The softening of V–V dimer in rutile phase was expected near MIT in previous theoretical and experimental work, which played an important role in the driving force of MIT. In this case, for the VO 2 /CH 3 NH 3 PbI 3 heterostructure as driven by not only heat but also extra injected electrons, the extending frontier of these extra electrons can only touch the vibrational region of the Raman‐active mode at 224 cm −1 while leaving the one at 194 cm −1 incapable to affect.…”

“…Among the well‐known substances in this class of materials is vanadium dioxide (VO 2 ), a solid featured by an electronic transition at 341 K as experimentally determined by Morin in 1959 . Despite a half‐century's accumulation of experimental observations and thus resulted in fundamentals on VO 2 , the description of the structural evolution pathway involved in the transition remains opaque, partly due to the complexity of the interplay between a set of active factors including charge, lattice and orbital . Until recently, some of the undiscovered mechanisms were being revealed by using advanced viewing tools capable of super high spatiotemporal resolutions .…”