Chemical functionalization is a promising route to band gap engineering of graphene. We chemically grafted nitrophenyl groups onto exfoliated single-layer graphene sheets in the form of substrate-supported or free-standing films. Our transport measurements demonstrate that non-suspended functionalized graphene behaves as a granular metal, with variable range hopping transport and a mobility gap ~ 0.1 eV at low temperature. For suspended graphene that allows functionalization on both surfaces, we demonstrate tuning of its electronic properties from a granular metal to a gapped semiconductor, in which charge transport occurs via thermal activation over a gap ~ 80 meV. This non-invasive and scalable functionalization technique paves the way for CMOS-compatible band gap engineering of graphene electronic devices.
@article{arxiv.1201.4384,
title = {Aryl Functionalization as a Route to Band Gap Engineering in Single Layer Graphene Devices},
author = {Hang Zhang and Elena Bekyarova and Jhao-Wun Huang and Zeng Zhao and Wenzhong Bao and Fenglin Wang and Robert C. Haddon and Chun Ning Lau},
journal= {arXiv preprint arXiv:1201.4384},
year = {2015}
}