| AVS 58th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Monday Sessions |
| Session GR-MoM |
| Session: | Graphene Growth |
| Presenter: | Shu Nie, Sandia National Laboratories |
| Authors: | S. Nie, Sandia National Laboratories J. Wofford, University of California at Berkeley and Lawrence Berkeley National Laboratory N.C. Bartelt, Sandia National Laboratories O. Dubon, University of California at Berkeley and Lawrence Berkeley National Laboratory K. McCarty, Sandia National Laboratories |
| Correspondent: | Click to Email |
Large area graphene growth on copper foils has attracted considerable interest because of the low cost and high graphene quality. However, relatively little is understood concerning the effect of substrate crystallographic orientation on the morphological evolution of graphene islands. Complication arises by the fact that the foil surface texture depends on how the foil is manufactured. In previous work we have examined graphene growth on the commonly occurring (100) surface of cold-rolled Cu foil.1 However, growth on the Cu(111) surface, another often observed orientation in textured Cu foil was not studied.
In this work we investigate graphene growth on single crystal Cu(111) in situ using a carbon evaporator in a low-energy electron microscope (LEEM). We find that graphene first nucleates at defects and impurities. A considerable fraction of the islands is misaligned in plane with the substrate, generating rotational boundaries upon inter-island impingement. Islands are dendritic with distinct lobes, similar to those reported on graphene/Cu(100).1 However, instead of each lobe being a graphene sheet with a different orientation, all lobes in an individual island form a single crystal. We propose that these dendritic shapes are the result of diffusion-limited growth. Consistent with this, we find that new island nucleation caused by an increase in the carbon flux occurs equidistant from existing islands. Furthermore, we show that the growth velocity of each lobe is accurately predicted by simulations assuming diffusion limited growth. This diffusion limited growth is in stark contrast with the large carbon attachment barriers seen on Ru and Ir.2 Unlike graphene growth on Ru(0001) and Ir(111),2 large densities of carbon adatoms are not detected before island nucleation. Temperature plays an important role in the crystallographic alignment of the graphene film. At high growth temperature (> 900 °C), graphene islands are found closely aligned with Cu, while at low temperature (< 800 °C), increased disorder in the orientation of graphene with respect to Cu(111) is observed in the low-energy diffraction patterns.
Work at Sandia and LBNL was supported by the Office of Basic Energy Sciences, Division of Materials Sciences and Engineering, U. S. Department of Energy under Contracts No. DE-AC04-94AL85000 and No. DE-AC02-05CH11231 respectively. JMW acknowledges support from the National Science Foundation Graduate Research Fellowship Program.
1. Wofford, J. M.; Nie, S.; McCarty, K. F.; Bartelt, N. C.; Dubon, O. D., Nano Lett., 10, 4890 (2010).
2. Loginova, E.; Bartelt, N. C.; Feibelman, P. J.; McCarty, K. F., New J. Phys. 10, 093026 (2008).