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Title: Anisotropic Electron-Photon and Electron-Phonon Interactions in Black Phosphorus

Orthorhombic black phosphorus (BP) and other layered materials, such as gallium telluride (GaTe) and tin selenide (SnSe), stand out among two-dimensional (2D) materials owing to their anisotropic in-plane structure. This anisotropy adds a new dimension to the properties of 2D materials and stimulates the development of angle-resolved photonics and electronics. However, understanding the effect of anisotropy has remained unsatisfactory to-date, as shown by a number of inconsistencies in the recent literatures. We use angle-resolved absorption and Raman spectroscopies to investigate the role of anisotropy on the electron-photon and electron-phonon interactions in BP. We highlight a non-trivial dependence between anisotropies and flake thickness, photon and phonon energies. We show that once understood, the anisotropic optical absorption appears to be a reliable and simple way to identify the crystalline orientation of BP, which cannot be determined from Raman spectroscopy without the explicit consideration of excitation wavelength and flake thickness, as commonly used previously.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [2] ;  [5] ;  [4] ;  [5] ;  [5] ;  [1] ;  [2] ;  [4] ;  [6] ;  [1]
  1. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  2. Tohoku Univ., Sendai (Japan)
  3. Rensselaer Polytechnic Inst., Troy, NY (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. Univ. of Pennsylvania, Philadelphia, PA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Rensselaer Polytechnic Inst., Troy, NY (United States)
Publication Date:
OSTI Identifier:
1257894
Grant/Contract Number:
SC0001299; AC05-00OR22725l; EFRI-1542815
Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 16; Journal Issue: 4; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE crystalline orientation; In-plane anisotropy; optical absorption; optical selection rule; Raman spectroscopy