Photoheat-induced Schottky nanojunction and indirect Mott transition in VO2: Photocurrent analysis

Hyun Tak Kim, Minjung Kim, Ahrum Sohn, Tetiana Slusar, Giwan Seo, Hyeonsik Cheong, Dong Wook Kim

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16 Scopus citations

Abstract

In order to elucidate a mechanism of the insulator-to-metal transition (IMT) for a Mott insulator VO2 (3d 1), we present Schottky nanojunctions and the structural phase transition (SPT) by simultaneous nanolevel measurements of photocurrent and Raman scattering in microlevel devices. The Schottky nanojunction with the monoclinic metallic phase between the monoclinic insulating phases is formed by the photoheat-induced IMT not accompanied with the SPT. The temperature dependence of the Schottky junction reveals that the Mott insulator has an electronic structure of an indirect subband between the main Hubbard d bands. The IMT as reverse process of the Mott transition occurs by temperature-induced excitation of bound charges in the indirect semiconductor band, most likely formed by impurities such as oxygen deficiency. The metal band (3d 1) for the Mott insulator is screened (trapped) by the indirect band (impurities).

Original languageEnglish
Article number085602
JournalJournal of Physics Condensed Matter
Volume28
Issue number8
DOIs
StatePublished - 1 Feb 2016

Keywords

  • metal-insulator transition
  • Mott transition
  • Schottky junction
  • VO

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