The role of momentum-dark excitons in the elementary optical response of bilayer WSe2
Journal article, 2018
Monolayer transition metal dichalcogenides (TMDs) undergo substantial changes in the single-particle band structure and excitonic optical response upon the addition of just one layer. As opposed to the single-layer limit, the bandgap of bilayer (BL) TMD semiconductors is indirect which results in reduced photoluminescence with richly structured spectra that have eluded a detailed understanding to date. Here, we provide a closed interpretation of cryogenic emission from BL WSe2as a representative material for the wider class of TMD semiconductors. By combining theoretical calculations with comprehensive spectroscopy experiments, we identify the crucial role of momentum-indirect excitons for the understanding of BL TMD emission. Our results shed light on the origin of quantum dot formation in BL crystals and will facilitate further advances directed at opto-electronic applications of layered TMD semiconductors in van der Waals heterostructures and devices.
Author
Jessica Lindlau
Ludwig-Maximilians-Universität München
Malte Selig
Chalmers, Physics, Condensed Matter Theory
Technische Universität Berlin
Andre Neumann
Ludwig-Maximilians-Universität München
Léo Colombier
Ludwig-Maximilians-Universität München
Jonathan Förste
Ludwig-Maximilians-Universität München
Victor Funk
Ludwig-Maximilians-Universität München
Michael Förg
Ludwig-Maximilians-Universität München
Jonghwan Kim
University of California
Gunnar Berghäuser
Chalmers, Physics, Condensed Matter Theory
Takashi Taniguchi
National Institute for Materials Science (NIMS)
Kenji Watanabe
National Institute for Materials Science (NIMS)
Feng Wang
University of California
Ermin Malic
Chalmers, Physics, Condensed Matter Theory
Alexander Högele
Ludwig-Maximilians-Universität München
Nature Communications
2041-1723 (ISSN)
Vol. 9 1 2586Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1038/s41467-018-04877-3