Events Calendar

AME Seminar

Speaker: Dr. Suneel Kodambaka, Assistant Professor, Materials Science and Engineering, University of California at Los Angeles

Talk Title: In situ Microscopy and Spectroscopy Studies of Epitaxial Graphene on Metal Surfaces

Abstract:

The recent discovery of two-dimensional (2D) graphene crystals has generated a lot of attention owing to its potential for applications in high-performance, low-power, electronics and as transparent conductors. Recent efforts focused on, and succeeded in, the fabrication of large-area graphene on a variety of substrates, an encouraging step toward realization of graphene-based devices. Yet, relatively little is known concerning the mechanisms underlying the growth of graphene and the role of substrate-graphene interactions on its electronic properties. As a first step, we focused on the development of an atomic-scale understanding of the growth and electronic structure of graphene on model metals such as Pd and Ni.

Using scanning tunneling microscopy and spectroscopy (STM and STS), in combination with density functional theory (DFT), we investigated the morphology and electronic structure of monolayer graphene grown on Pd(111) and on 3D facetted Ni islands. On Pd(111), we observe the formation of monolayer graphene islands, 200-2000 Å in size, bounded by Pd surface steps. Surprisingly, we found that graphene islands, as large as 2000 Å, are semiconducting with a bandgap of 0.3 eV. For graphene on Ni, we observed hexagonal and stripe moiré patterns with periodicities of 22 Å and 12 Å, respectively, on (111) and (110) facets of the islands. Graphene domains are also observed to grow, as single crystals, across adjacent facets and over facet boundaries. STS data indicate that the graphene layers are metallic on both Ni(111) and Ni(110). DFT calculations support all of our observations and indicate the presence of strong interactions between carbon and metal atoms. Our results suggest that electronic properties of epitaxial graphene can be tailored by the appropriate choice of substrate and the possibility of preparing large-area epitaxial graphene layers even on polycrystalline surfaces.


Host: Dr. A. Hodge

More Info: http://ame-www.usc.edu/seminars/index.shtml#upcoming

Location: John Stauffer Science Lecture Hall (SLH) - 100

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ame-www.usc.edu/seminars/index.shtml#upcoming