| AVS 55th International Symposium & Exhibition | |
| Graphene Topical Conference | Tuesday Sessions |
| Session GR+TF+NC-TuA |
| Session: | Graphene: Characterization, Properties, and Application |
| Presenter: | K.J. Cho, University of Texas at Dallas |
| Authors: | K.J. Cho, University of Texas at Dallas G. Lee, University of Texas at Dallas |
| Correspondent: | Click to Email |
Using the ab initio density functional theory (DFT), tight-binding (TB), and non-equilibrium Green’s function (NEGF) methods, we have studied the electronic properties of graphene oxides (GOs) and graphene nanoribbons (GNRs). Dry oxidation of graphene induces epoxide groups on the basal plane, and the corresponding electronic structures of GOs show directional band gap opening. We found that GOs have small energy gaps due to the lattice distortion at low oxygen coverage θO, and that they become semiconductors for θO ≥1/2 with the larger gap at the higher θO (Eg=3.3 eV at θO=1). However, for intermediate coverage, GOs become metallic along one zigzag direction while opening directional energy gaps along other zigzag directions depending on O adsorption patterns. We apply the percolation theory and NEGF method to explain the electron transport behavior of GOs. The insulating property of GOs is used to explain the inactive edge width of GNRs which are observed in GNR experimental studies. Electronic properties of GNRs are shown to have strong dependence on the edge chemistry indicating a practical challenge in graphene nanoelectronics using GNRs as channel materials.