Grain boundaries in graphene on SiC(0001¯) substrate
Résumé
Grain boundaries in epitaxial graphene on the SiC(0001¯) substrate are studied using scanning tunneling microscopy and spectroscopy. All investigated small-angle grain boundaries show pronounced out-of-plane buckling induced by the strain fields of constituent dislocations. The ensemble of observations determines the critical misorientation angle of buckling transition θc = 19 ± 2°. Periodic structures are found among the flat large-angle grain boundaries. In particular, the observed θ = 33 ± 2° highly ordered grain boundary is assigned to the previously proposed lowest formation energy structural motif composed of a continuous chain of edge-sharing alternating pentagons and heptagons. This periodic grain boundary defect is predicted to exhibit strong valley filtering of charge carriers thus promising the practical realization of all-electric valleytronic devices. © 2014 American Chemical Society.
Mots clés
Density functional theory
Graphene
Periodic structures
Silicon carbide
Buckling transitions
Misorientation angle
Ordered grain boundaries
Out of plane buckling
Periodic grain boundaries
Scanning tunneling microscopy and spectroscopy
Scanning tunneling spectroscopy
Small-angle grain boundaries
Grain boundaries
chemical structure
chemistry
scanning tunneling microscopy
surface property
Graphite
Microscopy
Scanning Tunneling
Models
Molecular
Silicon
Surface Properties