| AVS 59th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Tuesday Sessions |
| Session GR+AS+NS+SP+SS-TuA |
| Session: | Graphene Characterization Including Microscopy and Spectroscopy |
| Presenter: | P. Tyagi, University at Albany - SUNY |
| Authors: | P. Tyagi, University at Albany - SUNY J.D. McNeilan, University at Albany - SUNY J. Abel, University at Albany - SUNY F.J. Nelson, University at Albany - SUNY Z.R. Robinson, University at Albany - SUNY R. Moore, University at Albany - SUNY A.C. Diebold, University at Albany - SUNY V.P. LaBella, University at Albany - SUNY C.A. Ventrice, Jr., University at Albany - SUNY A.A. Sandin, North Carolina State Univ. D.B. Dougherty, North Carolina State Univ. J.E. Rowe, North Carolina State Univ. C. Dimitrakopoulos, IBM T.J. Watson Res. Center A. Grill, IBM T.J. Watson Res. Center C.Y. Sung, IBM T.J. Watson Res. Center S. Chen, Univ. of Texas at Austin A. Munson, Univ. of Texas at Austin Y. Hao, Univ. of Texas at Austin C.W. Magnuson, Univ. of Texas at Austin R.S. Ruoff, Univ. of Texas at Austin |
| Correspondent: | Click to Email |
The electronic structure of graphene depends on the number of graphene layers and the stacking sequence between the layers. Therefore, it is important to have a non-destructive technique for analyzing the overlayer coverage of graphene directly on the growth substrate. We have developed a technique using angle-resolved XPS to determine the average graphene thickness directly on metal foil substrates and SiC substrates. Since monolayer graphene films can be grown on Cu substrates, these samples are used as a standard reference for a monolayer of graphene. HOPG is used as a standard reference for bulk graphite. The electron mean free path of the C-1s photoelectron is determined by analyzing the areas under the C-1s peaks of monolayer graphene/Cu and bulk graphite and results in a value of 12.3 ±0.8 Å. With this electron mean free path, the graphene coverage of a film of arbitrary thickness can be determined from the areas under the C-1s peaks of the sample of interest, the monolayer graphene/Cu, and HOPG samples. Analysis of graphene coverages for graphene films grown on Cu-Ni substrates shows that a uniform monolayer is first formed before the growth of a second layer. The thickness of both the graphene overlayer and intermediate buffer layer has been determined on 6H-SiC substrates. Raman spectroscopy data have also been taken on these samples and compared to the overlayer coverages determined with XPS. This research was supported in part by the National Science Foundation (grant no. 1006350/1006411).