Sharpened VO2 Phase Transition via Controlled Release of Epitaxial Strain

Daesu Lee, Jaeseong Lee, Kyung Song, Fei Xue, Si Young Choi, Yanjun Ma, Jacob Podkaminer, Dong Liu, Shih Chia Liu, Bongwook Chung, Wenjuan Fan, Sang June Cho, Weidong Zhou, Jaichan Lee, Long Qing Chen, Sang Ho Oh, Zhenqiang Ma, Chang Beom Eom

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

Phase transitions in correlated materials can be manipulated at the nanoscale to yield emergent functional properties, promising new paradigms for nanoelectronics and nanophotonics. Vanadium dioxide (VO2), an archetypal correlated material, exhibits a metal-insulator transition (MIT) above room temperature. At the thicknesses required for heterostructure applications, such as an optical modulator discussed here, the strain state of VO2 largely determines the MIT dynamics critical to the device performance. We develop an approach to control the MIT dynamics in epitaxial VO2 films by employing an intermediate template layer with large lattice mismatch to relieve the interfacial lattice constraints, contrary to conventional thin film epitaxy that favors lattice match between the substrate and the growing film. A combination of phase-field simulation, in situ real-time nanoscale imaging, and electrical measurements reveals robust undisturbed MIT dynamics even at preexisting structural domain boundaries and significantly sharpened MIT in the templated VO2 films. Utilizing the sharp MIT, we demonstrate a fast, electrically switchable optical waveguide. This study offers unconventional design principles for heteroepitaxial correlated materials, as well as novel insight into their nanoscale phase transitions.

Original languageEnglish (US)
Pages (from-to)5614-5619
Number of pages6
JournalNano letters
Volume17
Issue number9
DOIs
StatePublished - Sep 13 2017

All Science Journal Classification (ASJC) codes

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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    Lee, D., Lee, J., Song, K., Xue, F., Choi, S. Y., Ma, Y., Podkaminer, J., Liu, D., Liu, S. C., Chung, B., Fan, W., Cho, S. J., Zhou, W., Lee, J., Chen, L. Q., Oh, S. H., Ma, Z., & Eom, C. B. (2017). Sharpened VO2 Phase Transition via Controlled Release of Epitaxial Strain. Nano letters, 17(9), 5614-5619. https://doi.org/10.1021/acs.nanolett.7b02482