期刊
JOURNAL OF CHEMICAL PHYSICS
卷 130, 期 7, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3077295
关键词
ab initio calculations; adhesion; density functional theory; graphene; interface structure; ruthenium; thermodynamics
资金
- Office of Basic Energy Sciences
- U. S. Department of Energy [DE-AC05-00OR22725, DEAC0205CH11231]
- Office of Nonproliferation Research and Development [NA22]
- U. S. Department of Energy
Annealing the Ru metal that typically contains residual carbon impurities offers a facile way to grow graphene on Ru(0001) at the macroscopic scale. Two superstructures of the graphene/Ru(0001) interface with periodicities of 3.0 and 2.7 nm, respectively, were previously observed by scanning tunneling microscopy. Using first principles density functional theory, we optimized the observed superstructures and found interfacial C-Ru bonding of C atoms atop Ru atoms for both superstructures, which causes the graphene sheet to buckle and form periodic humps of similar to 1.7 A in height within the graphene sheet. The flat region of the graphene sheet, which is 2.2-2.3 A above the top Ru layer and has more C atoms occupying the atop sites, interacts more strongly with the substrate than does the hump region. We found that interfacial adhesion is much stronger for the 3.0 nm superstructure than for the 2.7 nm superstructure, suggesting that the former is the thermodynamically more stable phase. We explained the 3.0 nm superstructure's stability in terms of the interplay between C-Ru bonding and lattice matching.
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