Pump-probe STM light emission spectroscopy for detection of photo-induced semiconductor-metal phase transition of VO2

Joe Sakai, Satoshi Katano, Masashi Kuwahara, Yoichi Uehara

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

We attempted to observe pump-probe scanning tunneling microscopy (STM)-light emission (LE) from a VO2 thin film grown on a rutile TiO2(0 0 1) substrate, with an Ag tip fixed over a semiconducting domain. Laser pulses from a Ti:sapphire laser (wavelength 920 nm; pulse width less than 1.5 ps) irradiated the tip-sample gap as pump and probe light sources. With a photon energy of 2.7 eV, suggesting phase transition from semiconducting monoclinic (M) to metallic rutile (R) phases in relation to the electronic band structure, faint LE was observed roughly 30 ps after the irradiation of the pump pulse, followed by retention for roughly 20 ps. The incident energy fluence of the pump pulse at the gap was five orders of magnitude lower than the threshold value for reported photo-induced M-R phase transition. The mechanism that makes it possible to reduce the threshold fluence is discussed.

Original languageEnglish
Article number405001
JournalJournal of Physics Condensed Matter
Volume29
Issue number40
DOIs
Publication statusPublished - 2017 Aug 31

Keywords

  • VO
  • light emission
  • pulsed laser deposition
  • scanning tunneling microscopy
  • thin films
  • time-resolved spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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