Year: 2025
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide The threshold switch operated by a field-driven insulator-to-metal transition in VO 2 has attracted considerable interest for emerging devices due to its nonlinear and sensitive response to external voltage. However, the nucleation barrier intrinsic to the first-order phase transition causes a finite time delay before the abrupt rise in currents under voltage pulses, thereby hindering energy-efficient device operation. Here, we demonstrate that the strain-graded VO 2 epilayer on Pt nanoislands (NIs) enables percolation-limited threshold switching by promoting the nucleation process of metallic phases during voltage-triggered phase transitions. Unlike constantly strained VO 2, the Pt NIs locally disrupt lattice coherency at the VO 2 /TiO 2 interface, facilitating gradual relaxation of misfit strain energy; tailoring the spatial strain distribution in the strain-graded VO 2 films effectively lowers the activation barrier for the nucleation events of metallic domains, achieving one-twentieth lower incubation time (τ inc ) compared to constantly strained VO 2 films. Moreover, this percolation-limited phase evolution stabilizes an intermediate metastable phase (i.e., negative differential resistance), enabling robust self-oscillatory behavior across a wide current range with enhanced tunability and dynamic controllability. These findings tailor the phase transition dynamics for ultrafast and energy-efficient switching applications.
Source: ACS Nano
Authors: Utaek Cho, Dong Kyu Lee, Sungwon Lee, Junwoo Son
Institutions: Seoul National University, University of Minnesota
Language: English
Subfield: Polymers and Plastics
Field: Materials Science
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
OpenAlex ID: W7117560053