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Title: Colloquium: Excitons in atomically thin transition metal dichalcogenides

Atomically thin materials such as graphene and monolayer transition metal dichalcogenides (TMDs) exhibit remarkable physical properties resulting from their reduced dimensionality and crystal symmetry. The family of semiconducting transition metal dichalcogenides is an especially promising platform for fundamental studies of two-dimensional (2D) systems, with potential applications in optoelectronics and valleytronics due to their direct band gap in the monolayer limit and highly efficient light-matter coupling. A crystal lattice with broken inversion symmetry combined with strong spin-orbit interactions leads to a unique combination of the spin and valley degrees of freedom. In addition, the 2D character of the monolayers and weak dielectric screening from the environment yield a significant enhancement of the Coulomb interaction. The resulting formation of bound electron-hole pairs, or excitons, dominates the optical and spin properties of the material. In this article, recent progress in understanding of the excitonic properties in monolayer TMDs is reviewed and future challenges are laid out. Discussed are the consequences of the strong direct and exchange Coulomb interaction, exciton light-matter coupling, and influence of finite carrier and electron-hole pair densities on the exciton properties in TMDs. Finally, the impact on valley polarization is described and the tuning of the energies and polarization observedmore » in applied electric and magnetic fields is summarized.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [5] ;  [5]
  1. Univ. of Toulouse (France). INSA-CNRS-UPS, LPCNO; Univ. of Cambridge (United Kingdom). G. W. Cambridge Graphene Centre
  2. Univ. of Regensburg (Germany). Dept. of Physics
  3. Ioffe Inst., St. Petersburg (Russian Federation)
  4. Stanford Univ., CA (United States). Dept. of Applied Physics; SLAC National Accelerator Lab., Menlo Park, CA (United States)
  5. Univ. of Toulouse (France). INSA-CNRS-UPS, LPCNO
Publication Date:
Grant/Contract Number:
CH 1672/1-1; 17-02-00383; 17-52-16020; AC02-76-SFO0515; 306719; GBMF4545; MD-1555.2017.2; SFB 1277, B05
Type:
Accepted Manuscript
Journal Name:
Reviews of Modern Physics
Additional Journal Information:
Journal Volume: 90; Journal Issue: 2; Journal ID: ISSN 0034-6861
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Chemical Sciences, Geosciences & Biosciences Division; European Research Council (ERC); German Research Foundation (DFG); Grant of the President of the Russian Federation; Russian Foundation for Basic Research; Gordon and Betty Moore Foundation; National Research Agency of France (ANR); Univ. Inst. of France (IUF); LIA CNRS-Ioffe ILNACS
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; optoelectronics; semiconductors; valleytronics
OSTI Identifier:
1435910