Electro-oxidized Epitaxial Graphene Channel Field-Effect Transistors with Single-Walled Carbon Nanotube Thin Film Gate Electrode

Palanisamy Ramesh (1) , Mikhail E. Itkis (1) , Elena Bekyarova (1) , Feihu Wang (1) , Sandip Niyogi (1) , Xiaoliu Chi (1) , Claire Berger (2) , Walt. A. de Heer (3) , Robert C. Haddon (1)

1 Center for Nanoscale Science and Engineering [Riverside]
2 NEEL - QuantECA - Circuits électroniques quantiques Alpes
3 School of Physics

We report the effect of electrochemical oxidation in nitric acid on the electronic properties of epitaxial graphene (EG) grown on silicon carbide substrates; we demonstrate the availability of an additional reaction channel in EG, which is not present in graphite but which facilitates the introduction of the reaction medium into the graphene galleries during electro-oxidation. The device performance of the chemically processed graphene was studied by patterning the EG wafers with two geometrically identical macroscopic channels; the electro-oxidized channel showed a logarithmic increase of resistance with decreasing temperature, which is ascribed to the scattering of charge carriers in a two-dimensional electronic gas, rather than the presence of an energy gap at the Fermi level. Field-effect transistors were fabricated on the electro-oxidized and pristine graphene channels using single-walled carbon nanotube thin film top gate electrodes, thereby allowing the study of the effect of oxidative chemistry on the transistor performance of EG. The electro-oxidized channel showed higher values for the on-off ratio and the mobility of the graphene field-effect transistor, which we ascribe to the availability of high-quality internal graphene layers after electro-oxidation of the more defective top layers. Thus, the present oxidative process provides a clear contrast with previously demonstrated covalent chemistry in which sp3 hybridized carbon atoms are introduced into the graphitic transport layer of the lattice by carbon-carbon bond formation, thereby opening an energy gap.

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Palanisamy Ramesh, Mikhail E. Itkis, Elena Bekyarova, Feihu Wang, Sandip Niyogi, et al.. Electro-oxidized Epitaxial Graphene Channel Field-Effect Transistors with Single-Walled Carbon Nanotube Thin Film Gate Electrode. Journal of the American Chemical Society, 2010, 132, pp.14429-14436. ⟨10.1021/ja101706j⟩. ⟨hal-01002945⟩