We present a first-principles study of the migration and recombination of edge defects (carbon adatom and/or vacancy) and their influence on electrical conductance in zigzag graphene nanoribbons (ZGNRs). It is found that at room temperature, the adatom is quite mobile while the vacancy is almost immobile along the edge of ZGNRs. The recombination of an adatom-vacancy pair leads to a pentagon-heptagon ring defect structure having a lower energy than the perfect edge, implying that such an edge-defect can be formed spontaneously. This edge defect can suppresses the conductance of ZGNRs drastically, which provides some useful hints for understanding the observed semiconducting behavior of the fabricated narrow GNRs.
@article{arxiv.1009.0022,
title = {Spontaneous edge-defect formation and defect-induced conductance suppression in graphene nanoribbons},
author = {Jia Li and Zuanyi Li and Gang Zhou and Zhirong Liu and Jian Wu and Bing-Lin Gu and Jisoon Ihm and Wenhui Duan},
journal= {arXiv preprint arXiv:1009.0022},
year = {2010}
}