| AVS 55th International Symposium & Exhibition | |
| Graphene Topical Conference | Monday Sessions |
| Session GR+SS+NC-MoA |
| Session: | Materials Issues in Graphene from SiC |
| Presenter: | N. Sharma, Georgia Institute of Technology |
| Authors: | N. Sharma, Georgia Institute of Technology D. Oh, Georgia Institute of Technology M. Sprinkle, Georgia Institute of Technology C. Berger, CNRS Grenoble, France W.A. deHeer, Georgia Institute of Technology T.M. Orlando, Georgia Institute of Technology P.N. First, Georgia Institute of Technology |
| Correspondent: | Click to Email |
Growth of high quality epitaxial graphene (EG) films on the basal plane of hexagonal SiC has been demonstrated previously, providing a potential route to wafer-scale graphene electronics. To realize this promise requires a detailed understanding of the atomic and electronic structure of the EG/SiC interface. For typical EG samples, STM measurements indicate a reconstructed interface (layer 0) covered by a layer (layer 1) that images as graphene (a honeycomb pattern) at low bias voltages, but appears to partially hybridize with interface states. For this layer, we also observe a strong suppression of the 2D Raman peak (also known as D* or G’) that is characteristic of graphene. For the second EG layer, a single Lorentzian-shape 2D peak is observed, which may indicate some isolation of layer 2 from the material below. Graphene films grown on the SiC (0001) surface are intrinsically electron doped. The screening response of the 2D electron gas in EG is expected to be unique due to the small carrier density and novel electronic structure. We use local defects and deposited metal islands to locally change the carrier density, and scanning tunneling spectroscopy to probe the screening response. This is of interest since the screening region in EG could include a transition from hole to electron doping, resulting in a surface PN junction that could influence electrical transport in this system.