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Title: Electron dynamics of the buffer layer and bilayer graphene on SiC

Angle- and time-resolved two-photon photoemission (TPPE) was used to investigate electronic states in the buffer layer of 4H-SiC(0001). An image potential state (IPS) series was observed on this strongly surface-bound buffer layer, and dispersion measurements indicated free-electron-like behavior for all states in this series. These results were compared with TPPE taken on bilayer graphene, which also show the existence of a free-electron-like IPS series. Lifetimes for the n = 2, and n = 3 states were obtained from time-resolved TPPE; slightly increased lifetimes were observed in the bilayer graphene sample for the n = 2 the n = 3 states. Despite the large band gap of graphene at the center of the Brillouin zone, the lifetime results demonstrate that the graphene layers do not behave as a simple tunneling barrier, suggesting that the buffer layer and graphene overlayers play a direct role in the decay of IPS electrons.
Authors:
; ; ;  [1] ;  [2] ;  [3] ;  [4] ;  [2]
  1. Department of Chemistry, University of California at Berkeley, Berkeley, California 94720 (United States)
  2. (United States)
  3. Department of Chemistry, University of Minnesota Twin Cities, Minneapolis, Minnesota 55455 (United States)
  4. Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208 (United States)
Publication Date:
OSTI Identifier:
22300045
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 104; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; BRILLOUIN ZONES; BUFFERS; DIFFUSION BARRIERS; DISPERSIONS; ELECTRONS; GRAPHENE; LAYERS; LIFETIME; PHOTOEMISSION; PHOTONS; SILICON CARBIDES; SURFACES; TIME RESOLUTION; TUNNEL EFFECT