title: In situ probing of doping- and stress-mediated phase transitions in a single-crystalline VO₂ nanobeam by spatially resolved Raman spectroscopy.
abstract: We demonstrate an experimental in situ observation of the temperature-dependent evolution of doping- and stress-mediated structural phase transitions in an individual single-crystalline VO₂ nanobeam on a Au-coated substrate under exposure to hydrogen gas using spatially resolved Raman spectroscopy. The nucleation temperature of the rutile R structural phase in the VO₂ nanobeam upon heating under hydrogen gas was lower than that under air. The spatial structural phase evolution behavior along the length of the VO₂ nanobeam under hydrogen gas upon heating was much more inhomogeneous than that along the length of the same nanobeam under air. The triclinic T phase of the VO₂ nanobeam upon heating under hydrogen gas transformed to the R phase and this R phase was stabilized even at room temperature in air after sample cooling. In particular, after the VO₂ nanobeam with the R phase was annealed at approximately 250 °C in air, it exhibited the monoclinic M1 phase (not the T phase) at room temperature during heating and cooling cycles. These results were attributed to the interplay between hydrogen doping and stress associated with nanobeam-substrate interactions. Our study has important implications for engineering metal-insulator transition properties and developing functional devices based on VO₂ nanostructures through doping and stress.
authors.affiliation: Division of Materials Science, Korea Basic Science Institute, Daejeon 305-333, Korea.
authors.forename: Sung-Jin
authors.initials: SJ
authors.lastname: Chang
authors.forename: Jong Bae
authors.initials: JB
authors.lastname: Park
authors.forename: Gaehang
authors.initials: G
authors.lastname: Lee
authors.forename: Hae Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jin-Bae
authors.initials: JB
authors.lastname: Lee
authors.forename: Tae-Sung
authors.initials: TS
authors.lastname: Bae
authors.forename: Young-Kyu
authors.initials: YK
authors.lastname: Han
authors.forename: Tae Jung
authors.initials: TJ
authors.lastname: Park
authors.forename: Yun Suk
authors.initials: YS
authors.lastname: Huh
authors.forename: Woong-Ki
authors.initials: WK
authors.lastname: Hong