Layer-number determination in graphene on SiC by reflectance mapping

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Abstract

We report a simple, handy and affordable optical approach for precise number-of-layers determination of graphene on SiC based on monitoring the power of the laser beam reflected from the sample (reflectance mapping) in a slightly modified micro-Raman setup. Reflectance mapping is compatible with simultaneous Raman mapping. We find experimentally that the reflectance of graphene on SiC normalized to the reflectivity of bare substrate (the contrast) increases linearly with similar to 1.7% per layer for up to 12 layers, in agreement with theory The wavelength dependence of the contrast in the visible is investigated using the concept of ideal fermions and compared with existing experimental data for the optical constants of graphene. We argue also that the observed contrast is insensitive to the doping condition of the sample, as well as to the type of sample (graphene on C- or Si-face of 4H or 6H SiC, hydrogen-intercalated graphene). The possibility to extend the precise layer counting to similar to 50 layers makes reflectivity mapping superior to low-energy electron microscopy (limited to similar to 10 layers) in quantitative evaluation of graphene on the C-face of SiC. The method is applicable for graphene on other insulating or semiconducting substrates. (C) 2014 Elsevier Ltd. All rights reserved.

Detaljer

Författare
  • Ivan G. Ivanov
  • Jawad Ul Hassan
  • Tihomir Iakimov
  • Alexei Zakharov
  • Rositsa Yakimova
  • Erik Janzen
Enheter & grupper
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Fysik
  • Naturvetenskap
Originalspråkengelska
Sidor (från-till)492-500
TidskriftCarbon
Volym77
StatusPublished - 2014
PublikationskategoriForskning
Peer review utfördJa