Probing dark exciton navigation through a local strain landscape in a WSe2 monolayer
Abstract
In WSe2 monolayers, strain has been used to control the energy of excitons, induce funneling, and realize single-photon sources. Here, we developed a technique for probing the dynamics of free excitons in nanoscale strain landscapes in such monolayers. A nanosculpted tapered optical fiber is used to simultaneously generate strain and probe the near-field optical response of WSe2 monolayers at 5 K. When the monolayer is pushed by the fiber, its lowest energy states shift by as much as 390 meV (>20% of the bandgap of a WSe2 monolayer). Polarization and lifetime measurements of these red-shifting peaks indicate they originate from dark excitons. We conclude free dark excitons are funneled to high-strain regions during their long lifetime and are the principal participants in drift and diffusion at cryogenic temperatures. This insight supports proposals on the origin of single-photon sources in WSe2 and demonstrates a route towards exciton traps for exciton condensation.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jan 11, 2022
- Source ID
- 10.1038/s41467-021-27877-2
Entities
People
- Benjamin Pingault
- Bernhard Urbaszek
- Dylan Renaud
- Giovanni Scuri
- Hongkun Park
- Kenji Watanabe
- Marko Loncar
- Ryan J. Gelly
- Stefan Bogdanović
- Takashi Taniguchi
- Xing Liao
Organizations
- Army Research Office
- National Science Foundation
- Office of Naval Research
- Samsung Group
- United States Army Research Laboratory
- United States Department of Defense
- United States Department of Energy