| AVS 56th International Symposium & Exhibition | |
| Graphene Topical Conference | Wednesday Sessions |
| Session GR+AS-WeA |
| Session: | Graphene: Surface Characterization |
| Presenter: | S. Kodambaka, University of California, Los Angeles |
| Authors: | S. Kodambaka, University of California, Los Angeles S.-Y. Kwon, University of California, Los Angeles C.V. Ciobanu, Colorado School of Mines V. Petrova, University of Illinois J. Bareno, University of Illinois V.B. Shenoy, Brown University V. Gambin, Northrop Grumman Space and Technology I. Petrov, University of Illinois |
| Correspondent: | Click to Email |
We report in situ variable-temperature scanning tunneling microscopy studies of graphene growth on Pd(111) during ethylene deposition at temperatures between 723 and 1023 K. We observe the formation of monolayer graphene islands, 200-2000 Å in size, bounded by Pd surface steps. Surprisingly, the topographic image contrast from graphene islands reverses with tunneling bias, suggestive of a semiconducting behavior. Scanning tunneling spectroscopy measurements confirm that the graphene islands are semiconducting, with a bandgap of 0.3±0.1 eV. Using density functional theory calculations, we attribute this phenomenon to the breaking of hexagonal symmetry due to a strong interaction between graphene and the nearly commensurate Pd substrate. Our findings suggest the possibility of preparing semiconducting graphene layers for future carbon-based nanoelectronic devices via direct deposition onto strongly interacting substrates.