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Title: Real-time observation of epitaxial graphene domain reorientation

Graphene films grown by vapour deposition tend to be polycrystalline due to the nucleation and growth of islands with different in-plane orientations. Here, using low-energy electron microscopy, we find that micron-sized graphene islands on Ir(111) rotate to a preferred orientation during thermal annealing. We observe three alignment mechanisms: the simultaneous growth of aligned domains and dissolution of rotated domains, that is, ‘ripening’; domain boundary motion within islands; and continuous lattice rotation of entire domains. By measuring the relative growth velocity of domains during ripening, we estimate that the driving force for alignment is on the order of 0.1 meV per C atom and increases with rotation angle. A simple model of the orientation-dependent energy associated with the moiré corrugation of the graphene sheet due to local variations in the graphene–substrate interaction reproduces the results. This study suggests new strategies for improving the van der Waals epitaxy of 2D materials.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  2. Univ. of California, Berkeley, CA (United States)
  3. (LBNL), Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1235318
Report Number(s):
SAND--2015-2564J
Journal ID: ISSN 2041-1723; 579878
Grant/Contract Number:
AC04-94AL85000
Type:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 6; Journal Issue: 4; Journal ID: ISSN 2041-1723
Publisher:
Nature Publishing Group
Research Org:
Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
physical sciences; materials science; nanotechnology