We report catalyst-free direct synthesis of vertical graphene nanosheets (VGNs) on SiO2/Si and quartz substrates using microwave electron cyclotron resonance - plasma enhanced chemical vapor deposition. The evolution of VGNs is studied systematically at different growth stages. Raman analysis as a function of growth time reveals that two different disorder-induced competing mechanisms contributing to the defect band intensity. The VGNs grown on SiO2/Si substrates predominantly consists of both vacancy-like and hopping defects. On the other hand, the VGNs grown on quartz substrates contain mainly boundary-like defects. XPS studies also corroborate Raman analysis in terms of defect density and vacancy-like defects for the VGNs grown on SiO2/Si substrates. Moreover, the grown VGNs exhibit a high optical transmittance from 95 to 78 % at 550 nm and the sheet resistance varies from 30 to 2.17 kohms/square depending on growth time.
@article{arxiv.1402.2074,
title = {Evolution and defect analysis of vertical graphene nanosheets},
author = {Subrata Ghosh and K. Ganesan and Shyamal R. Polaki and T. R. Ravindran and Nanda Gopala Krishna and M. Kamruddin and A. K. Tyagi},
journal= {arXiv preprint arXiv:1402.2074},
year = {2015}
}
Comments
19 pages, 8 figures, 1 table; Accepted in Journal of Raman Spectroscopy (2014)