Flat-Band-Induced Many-Body Interactions and Exciton Complexes in a Layered Semiconductor
Journal article, 2022
Interactions among a collection of particles generate many-body effects in solids that result in striking modifications of material properties. The heavy carrier mass that yields strong interactions and gate control of carrier density over a wide range makes two-dimensional semiconductors an exciting playground to explore many-body physics. The family of III-VI metal monochalcogenides emerges as a new platform for this purpose because of its excellent optical properties and the flat valence band dispersion. In this work, we present a complete study of charge-tunable excitons in few-layer InSe by photoluminescence spectroscopy. From the optical spectra, we establish that free excitons in InSe are more likely to be captured by ionized donors leading to the formation of bound exciton complexes. Surprisingly, a pronounced red shift of the exciton energy accompanied by a decrease of the exciton binding energy upon hole-doping reveals a significant band gap renormalization induced by the presence of the Fermi reservoir.
many-body interactions
photoluminescence spectroscopy
indium selenide
excitons
two-dimensional materials
Author
Gabriele Pasquale
Swiss Federal Institute of Technology in Lausanne (EPFL)
Zhe Sun
Swiss Federal Institute of Technology in Lausanne (EPFL)
Kristiā Ns Čerņevičs
Swiss Federal Institute of Technology in Lausanne (EPFL)
Raul Perea Causin
Chalmers, Physics, Condensed Matter and Materials Theory
Fedele Tagarelli
Swiss Federal Institute of Technology in Lausanne (EPFL)
Kenji Watanabe
National Institute for Materials Science (NIMS)
Takashi Taniguchi
National Institute for Materials Science (NIMS)
Ermin Malic
Chalmers, Physics, Condensed Matter and Materials Theory
Philipps University Marburg
Oleg V. Yazyev
Swiss Federal Institute of Technology in Lausanne (EPFL)
A. Kis
Swiss Federal Institute of Technology in Lausanne (EPFL)
Nano Letters
1530-6984 (ISSN) 1530-6992 (eISSN)
Vol. 22 22 8883-8891Subject Categories
Atom and Molecular Physics and Optics
Other Physics Topics
Condensed Matter Physics
DOI
10.1021/acs.nanolett.2c02965