Аннотация
We used scanning tunneling microscopy and spectroscopy (STM/S)
techniques to analyze the relationships between the edge shapes and the
electronic structures in as-grown chemical vapor deposition (CVD)
graphene nanoribbons (GNRs). A rich variety of single-layered graphene
nanoribbons exhibiting a width of several to 100 nm and up to 1 mu m
long were studied. High-resolution STM images highlight highly
crystalline nanoribbon structures with well-defined and clean edges.
Theoretical calculations indicate clear spin-split edge states induced
by electron electron Coulomb repulsion. The edge defects can
significantly modify these edge states, and different edge structures
for both sides of a single ribbon produce asymmetric electronic edge
states, which reflect the more realistic features of CVD grown GNRs.
Three structural models are proposed and analyzed to explain the
observations. By comparing the models with an atomic resolution image at
the edge, a pristine (2,1) structure was ruled out in favor of a
reconstructed edge structure composed of 5-7 member rings, showing a
better match with experimental results, and thereby suggesting the
possibility of a defective morphology at the edge of CVD grown
nanoribbons.
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