Optical Probing of Electronic Interaction between Graphene and Hexagonal Boron Nitride (hBN)

  • Ahn, Gwanghyun (Department of Applied Chemistry, Kyung Hee University) ;
  • Kim, Hye Ri (SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface Nano Technology (HINT) and Department of Chemistry, Sungkyunkwan University) ;
  • Ko, Taeg Yeoung (Department of Applied Chemistry, Kyung Hee University) ;
  • Choi, Kyoungjun (SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface Nano Technology (HINT) and Department of Chemistry, Sungkyunkwan University) ;
  • Watanabe, Kenji (National Institute for Materials Science) ;
  • Taniguchi, Takashi (National Institute for Materials Science) ;
  • Hong, Byung Hee (SKKU Advanced Institute of Nanotechnology (SAINT), Center for Human Interface Nano Technology (HINT) and Department of Chemistry, Sungkyunkwan University) ;
  • Ryu, Sunmin (Department of Applied Chemistry, Kyung Hee University)
  • Published : 2013.02.18

Abstract

Even weak van der Waals (vdW) adhesion between two-dimensional solids may perturbtheir various materials properties owing to their low dimensionality. Although the electronic structure of graphene has been predicted to be modified by the vdW interaction with other materials, its optical characterization has not been successful. In this report, we demonstrate that Raman spectroscopy can be utilized to detect a few % decrease in the Fermi velocity ($v_F$) of graphene caused by the vdW interaction with underlying hexagonal boron nitride (hBN). Our study also establishes Raman spectroscopic analysis which enables separation of the effects by the vdW interaction from those by mechanical strain or extra charge carriers. The analysis reveals that spectral features of graphene on hBN are mainly affected by change in vF and mechanical strain, but not by charge doping unlike graphene supported on $SiO_2$ substrates. Graphene on hBN was also found to be less susceptible to thermally induced hole doping.

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