Paper GR+TF-TuA4
Electrical Transport in Graphenoid and Graphene Nanomembranes from Pyrolized Self-Assembled Monolayers

Tuesday, October 19, 2010, 3:00 pm, Room Brazos

Ultrathin carbon nanomembranes have recently attracted enormous interest. We report a molecular route to the fabrication of a monolayer or few layers of free-standing graphenoid and graphene nanomembranes based on molecular self-assembly, electron processing and pyrolysis. Aromatic biphenyl self-assembled monolayers (SAMs) are cross-linked by electron irradiation. The cross-linking results in mechanically stable graphenoid sheets with the thickness of a single molecule (~1 nm) and arbitrary sized. The graphenoid sheets can be lifted from their surface and transferred to another solid substrate or holey structures, where they become free-standing nanomembranes. Upon annealing (pyrolysis) up to 1300 K the molecular sheets transform into nanocrystalline graphene phase. This transformation is accompanied by a drop of the sheet resistivity from ~10⁸ to ~10 kΩ/sq and a 2D insulator to metal transition. We characterize the insulator to metal transition by electrical transport measurements as well as by complementary spectroscopic and microscopic techniques. A plethora of applications of the suggested molecular route to free-standing ultrathin carbon materials is feasible that take advantage from the fact that the large scale fabrication, control over the thickness and nanostructuring are easily controlled.

[1] A. Turchanin, A. Beyer, C. T. Nottbohm, X. H. Zhang, R. Stosch, A. Sologubenko, J. Mayer, P. Hinze, T. Weimann, and A. Gölzhäuser: One Nanometer Thin Carbon Nanosheets with Tunable Conductivity and Stiffness, Adv. Mater. 21, 1233-1237 (2009)

[2] A. Turchanin, D. Käfer, M. El-Desawy, C. Wöll, G. Witte, and A. Gölzhäuser: Molecular Mechanisms of Electron-Induced Cross-Linking in Aromatic SAMs, Langmuir 25, 7342-7352 (2009).