AVS 60th International Symposium and Exhibition
    Graphene and Other 2D Materials Focus Topic Thursday Sessions
       Session GR-ThP

Paper GR-ThP9
The Robustness of the Electronic Structures of the Quasi-Free Standing Graphene Layers Upon Deposition of the Strong Hole-Doping Materials

Thursday, October 31, 2013, 6:00 pm, Room Hall B

Session: Graphene and Other 2D Materials Poster Session
Presenter: W. Kim, Korea Research Institute of Standards and Science, Republic of Korea
Authors: W. Kim, Korea Research Institute of Standards and Science, Republic of Korea
G.-E. Yang, Kyung Hee University, Republic of Korea
J. Kim, Kyung Hee University, Republic of Korea
Y. Park, Kyung Hee University, Republic of Korea
B.-G. Park, Pohang Accelerator Laboratory, Republic of Korea
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We investigated the change in the electronic structure of the quasi-free standing epitaxial graphene(QFEG) layers upon deposition of strong hole doping materials by using angle-resolved photoemission spectroscopy(ARPES). To produce the QFEG layers, we tried hydrogen intercalation into a zero-layer graphene grown on the 4H-SiC(0001) surface, and confirmed the successful formation of the QFEG layers, judging from the coincidence of the Dirac point and Fermi levels in the ARPES spectra of the hydrogen-intercalated graphene layers. Then we monitored carefully the change of the position of Dirac point in ARPES spectra during the deposition of strong hole-doping materials such as Bi atoms and tetrafluoro-tetracyanoquinodimethane (4F-TCNQ) molecules, both of which are known to induce the significant shifts of the Dirac point to the Fermi level in the conventional epitaxial graphene layers. However, for the QFEG layers, we could not find any measurable shifts of Dirac point upon the deposition of Bi atoms or 4F-TCNQ up to the 1 ML thickness. The overall shape of graphene π -bands also remained almost same, unlikely the results for the conventional epitaxial graphene layers which show significant blurring of band width near 1 ML thickness. This robustness of the electronic structure of QFEG layer upon deposition of Bi atoms and 4F-TCNQ molecules implies that more sophisticated approach is required to understand the hole-doping effect in the conventional epitaxial graphene and QFEG layers grown on the SiC(0001) surface.