Structure and evolution of semiconducting buffer graphene grown on SiC(0001)

M. Conrad, J. Rault, Y. Utsumi, Y. Garreau, A. Vlad, A. Coati, J.-P. Rueff, P. F. Miceli, and E. H. Conrad
Phys. Rev. B 96, 195304 – Published 13 November 2017
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Abstract

Using highly controlled coverages of graphene on SiC(0001), we have studied the structure of the first graphene layer that grows on the SiC interface. This layer, known as the buffer layer, is semiconducting. Using x-ray reflectivity and x-ray standing wave analysis, we have performed a comparative study of the buffer layer structure with and without an additional monolayer graphene layer above it. We show that no more than 26% of the buffer carbon is covalently bonded to Si in the SiC interface. We also show that the top SiC bilayer is Si depleted and is likely the cause of the incommensuration previously observed in this system. When a monolayer graphene layer forms above the buffer, the buffer layer becomes less corrugated with signs of a change in the bonding geometry with the SiC interface. At the same time, the entire SiC interface becomes more disordered, presumably due to entropy associated with the higher growth temperature.

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  • Received 7 July 2017
  • Revised 29 August 2017

DOI:https://doi.org/10.1103/PhysRevB.96.195304

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

M. Conrad1, J. Rault2, Y. Utsumi2, Y. Garreau2,3, A. Vlad2, A. Coati2, J.-P. Rueff2, P. F. Miceli4, and E. H. Conrad1,*

  • 1Georgia Institute of Technology, Atlanta, Georgia 30332-0430, USA
  • 2Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91192 Gif sur Yvette, France
  • 3Université Paris Diderot, Sorbonne-Paris-Cité, MPQ, UMR 7162 CNRS, Bâtiment Condorcet, Case 7021, 75205 Paris Cedex 13, France
  • 4Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211, USA

  • *edward.conrad@physics.gatech.edu

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Issue

Vol. 96, Iss. 19 — 15 November 2017

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