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Title: Raman spectra and electron-phonon coupling in disordered graphene with gate-tunable doping

We report a Raman spectroscopy study of graphene field-effect transistors with a controlled amount of defects introduced in graphene by exposure to electron-beam irradiation. Raman spectra are taken at T = 8 K over a range of back gate voltages (V{sub g}) for various irradiation dosages (R{sub e}). We study effects in the Raman spectra due to V{sub g}-induced doping and artificially created disorder at various R{sub e}. With moderate disorder (irradiation), the Raman G peak with respect to the graphene carrier density (n{sub FE}) exhibits a minimum in peak frequency and a maximum in peak width near the charge-neutral point (CNP). These trends are similar to those seen in previous works on pristine graphene and have been attributed to a reduction of electron-phonon coupling strength (D) and removal of the Kohn anomaly as the Fermi level moves away from the CNP. We also observe a maximum in I{sub 2D}/I{sub G} and weak maximum in I{sub D}/I{sub G} near the CNP. All the observed dependences of Raman parameters on n{sub FE} weaken at stronger disorder (higher R{sub e}), implying that disorder causes a reduction of D as well. Our findings are valuable for understanding Raman spectra and electron-phonon physics in doped and disorderedmore » graphene.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [1] ;  [2] ;  [2]
  1. Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)
  2. (United States)
  3. Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana 47907 (United States)
Publication Date:
OSTI Identifier:
22402793
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; 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:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DOPED MATERIALS; ELECTRON BEAMS; ELECTRON-PHONON COUPLING; ELECTRONS; FERMI LEVEL; FIELD EFFECT TRANSISTORS; GRAPHENE; IRRADIATION; PEAKS; PHONONS; RAMAN SPECTRA; RAMAN SPECTROSCOPY