Probing Exciton Dispersions of Freestanding Monolayer WSe<sub>2</sub> by Momentum-Resolved Electron Energy-Loss Spectroscopy
- Author(s)
- Jinhua Hong, Ryosuke Senga, Thomas Pichler, Kazu Suenaga
- Abstract
Excitons, as bound electron-hole paired quasiparticle, play an essential role in the energy transport in the optical-electric properties of semiconductors. Their momentum-energy dispersion relation is a fundamental physical property of great significance to understand exciton dynamics. However, this dispersion is seldom explored especially in two-dimensional transition metal dichalcogenides with rich valleytronic properties. In this work, momentum resolved electron energy-loss spectroscopy was used to measure the dispersions of excitons in freestanding monolayer WSe2. Besides the parabolically dispersed valley excitons, a subgap dispersive exciton was observed at nonzero momenta for the first time, which can be introduced by the prolific Se vacancies. Our work provides a paradigm to directly probe exciton dispersions in 2D semiconductors and could be generalized to many low-dimensional systems.
- Organisation(s)
- Electronic Properties of Materials
- External organisation(s)
- National Institute of Advanced Industrial Science and Technology (AIST)
- Journal
- Physical Review Letters
- Volume
- 124
- No. of pages
- 5
- ISSN
- 0031-9007
- Publication date
- 09-2019
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103015 Condensed matter
- Keywords
- ASJC Scopus subject areas
- Physics and Astronomy(all)
- Portal url
- https://ucris.univie.ac.at/portal/en/publications/probing-exciton-dispersions-of-freestanding-monolayer-wse2-by-momentumresolved-electron-energyloss-spectroscopy(cebbc22d-a0a4-4de0-91f8-82ecc3326f3e).html