Year: 2019
Type: article
Abstract: Control over the concurrent occurrence of structural (monoclinic to tetragonal) and electrical (insulator to the conductor) transitions presents a formidable challenge for VO2-based thin film devices. Speed, lifetime, and reliability of these devices can be significantly improved by utilizing solely electrical transition while eliminating structural transition. We design a novel strain-stabilized isostructural VO2 epitaxial thin-film system where the electrical transition occurs without any observable structural transition. The thin-film heterostructures with a completely relaxed NiO buffer layer have been synthesized allowing complete control over strains in VO2 films. The strain trapping in VO2 thin films occurs below a critical thickness by arresting the formation of misfit dislocations. We discover the structural pinning of the monoclinic phase in (10 ± 1 nm) epitaxial VO2 films due to bandgap changes throughout the whole temperature regime as the insulator-to-metal transition occurs. Using density functional theory, we calculate that the strain in monoclinic structure reduces the difference between long and short V-V bond-lengths (ΔV−V) in monoclinic structures which leads to a systematic decrease in the electronic bandgap of VO2. This decrease in bandgap is additionally attributed to ferromagnetic ordering in the monoclinic phase to facilitate a Mott insulator without going through the structural transition.
Source: Scientific Reports
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,790
Awards: G122673668, G1286236842, G1286251239, G1314494723, G1414775356, G1445641779, G1609943340, G1677143136, ADVANCED CHARACTERIZATION OF FUNCTIONAL OXIDE INTERFACES, G1816284028, G1863003419, G2618837358, G30714459, G3083819904, G365575497, G3967535168, G4180763844, G419881185, G42916606, G4501827968, G498139845, GOALI: Novel Epitaxial Vanadium Oxide Thin Film Heterostructures Integrated with Si(100), G5076365615, G5296923526, G5849692847, G5922012458, G5971776692, G650090426, G6652958823, G7452299184, G805243471, G969889393
OpenAlex ID: W2919463145