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Title: Valley excitons in two-dimensional semiconductors

Monolayer group-VIB transition metal dichalcogenides have recently emerged as a new class of semiconductors in the two-dimensional limit. The attractive properties include: the visible range direct band gap ideal for exploring optoelectronic applications; the intriguing physics associated with spin and valley pseudospin of carriers which implies potentials for novel electronics based on these internal degrees of freedom; the exceptionally strong Coulomb interaction due to the two-dimensional geometry and the large effective masses. The physics of excitons, the bound states of electrons and holes, has been one of the most actively studied topics on these two-dimensional semiconductors, where the excitons exhibit remarkably new features due to the strong Coulomb binding, the valley degeneracy of the band edges, and the valley dependent optical selection rules for interband transitions. Here we give a brief overview of the experimental and theoretical findings on excitons in two-dimensional transition metal dichalcogenides, with focus on the novel properties associated with their valley degrees of freedom.
 [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Hong Kong (China). Dept. of Physics and Center of Theoretical and Computational Physics
  2. Univ. of Hong Kong (China). Dept. of Physics
  3. Univ. of Washington, Seattle, WA (United States). Dept. of Physics and Dept. of Material Science and Engineering
Publication Date:
OSTI Identifier:
Grant/Contract Number:
AC05-00OR22725; SC0008145
Accepted Manuscript
Journal Name:
National Science Review
Additional Journal Information:
Journal Volume: 2; Journal Issue: 1; Journal ID: ISSN 2095-5138
China Science Publishing
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States