In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We used scanning tunneling microscopy (STM), Raman spectroscopy, x-ray spectroscopy, and first principles calculations to characterize individual nitrogen dopants in monolayer graphene grown on a copper substrate. Individual nitrogen atoms were incorporated as graphitic dopants, and a fraction of the extra electron on each nitrogen atom was delocalized into the graphene lattice. The electronic structure of nitrogen-doped graphene was strongly modified only within a few lattice spacings of the site of the nitrogen dopant. These findings show that chemical doping is a promising route to achieving high-quality graphene films with a large carrier concentration.
@article{arxiv.1108.4026,
title = {Visualizing Individual Nitrogen Dopants in Monolayer Graphene},
author = {Liuyan Zhao and Rui He and Kwang Taeg Rim and Theanne Schiros and Keun Soo Kim and Hui Zhou and Christopher Gutiérrez and S. P. Chockalingam and Carlos J. Arguello and Lucia Pálová and Dennis Nordlund and Mark S. Hybertsen and David R. Reichman and Tony F. Heinz and Philip Kim and Aron Pinczuk and George W. Flynn and Abhay N. Pasupathy},
journal= {arXiv preprint arXiv:1108.4026},
year = {2011}
}