High Layer Uniformity of Two-Dimensional Materials Demonstrated Surprisingly from Broad Features in Surface Electron Diffraction

S Chen; M Horn von Hoegen; P A Thiel; A Kaminski; B Schrunk; T Speliotis; E H Conrad; M C Tringides

doi:10.1021/acs.jpclett.0c02113

High Layer Uniformity of Two-Dimensional Materials Demonstrated Surprisingly from Broad Features in Surface Electron Diffraction

J Phys Chem Lett. 2020 Nov 5;11(21):8937-8943. doi: 10.1021/acs.jpclett.0c02113. Epub 2020 Oct 8.

Authors

S Chen¹, M Horn von Hoegen², P A Thiel¹, A Kaminski¹, B Schrunk¹, T Speliotis³, E H Conrad⁴, M C Tringides¹

Affiliations

¹ Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States.
² Department of Physics and Center for Nanointegration CENIDE, University of Duisburg-Essen, Lotharstrasse 1, 47057 Duisburg, Germany.
³ Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi, 15310 Athens, Greece.
⁴ Department of Physics, Georgia Technology Institute, 837 State Street, Atlanta, Georgia 30332-0430, United States.

PMID: 32902297
DOI: 10.1021/acs.jpclett.0c02113

Abstract

Paradoxically, a very broad diffraction background, named the bell-shaped-component (BSC), has been established as a feature of graphene growth. Recent diffraction studies as a function of electron energy have shown that the BSC is not related to scattering interference. Here, additional experiments are carried out as a function of temperature over the range in which single-layer graphene (SLG) grows. Quantitative fitting of the profiles shows that the BSC follows the increase of the Gr(10) spot, proving directly that the BSC indicates high-quality graphene. Additional metal deposition experiments provide more information about the BSC. The BSC is insensitive to metal deposition, and it increases with metal intercalation, because a more uniform interface forms between graphene and SiC. These experiments support the conclusion that the BSC originates from electron confinement within SLG, and surprisingly, it is an excellent measure of graphene uniformity.