Issue 22, 2014 - USTC reveals graphene ordered grain boundary structure

USTC reveals graphene ordered grain boundary structure

Recently, the University of Science and Technology of China used scanning tunneling microscopy to study graphene ordered grain boundaries, revealing the ordered grain boundary structure resolved at the atomic scale, and proving the existence of van Hof singularity (VHS)
in ordered grain boundaries.
The findings were published in
Physical Review Letters.

A grain boundary is a structural defect in graphene materials that significantly affects its physical properties, especially conductivity and electron mobility
.
The researchers used scanning tunneling microscopy to characterize a variety of ordered grain boundary structures of graphene with atomic scale resolution, and demonstrated for the first time the electronic state (VHS state)
caused by van Hove singularity in ordered grain boundaries in graphene.

By comparing the electronic behavior of ordered grain boundaries and disordered grain boundaries in graphene, the differences between VHS states and local electronic states in disordered grain boundaries in ordered grain boundaries are analyzed, which is helpful to understand the conflicting results
in related transport studies.

Combined with theoretical calculations, it is shown that the VHS state can effectively increase the carrier concentration
of graphene.
Based on this result, the research group proposed a possible graphene band structure embedded with ordered grain boundaries, which can be used to improve the electron transport properties and device effects
of graphene band structure-based devices.

(Li Meng)