| AVS 59th Annual International Symposium and Exhibition | |
| Graphene and Related Materials Focus Topic | Wednesday Sessions |
| Session GR+AS+EM+NS+SS-WeA |
| Session: | Dopants and Defects in Graphene; Graphene Interfaces with Other Materials |
| Presenter: | A. Dahal, University of South Florida |
| Authors: | A. Dahal, University of South Florida A. Rafik, University of South Florida P.W. Sutter, Brookhaven National Laboratory M. Batzill, University of South Florida |
| Correspondent: | Click to Email |
Bi-layer graphene synthesis by chemical vapor deposition is of importance for field effect devices because the band gap can be tuned in bi-layer graphene by an applied electric field. Here, we demonstrate that bi-layer graphene can be synthesized above 650oC by chemical vapor deposition on thin Ni(111) films grown on YSZ(111) substrates in ultra high vacuum (UHV). We characterize the bi-layer graphene growth by low energy electron microscopy (LEEM), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). Below 600 oC graphene grows in registry with the Ni(111) lattice and no second layer graphene is formed upon cooling. At 650 oC rotationally misaligned graphene domains are formed on Ni(111) and we observe second layer graphene to grow by carbon-segregation under those rotated monolayer graphene domains. The difference in second layer graphene nucleation and growth is explained by the graphene-Ni interaction, which is much stronger for graphene in registry with the substrate than for rotated graphene. The segregated second layer graphene sheet is in registry with the Ni(111) substrate and this suppresses further carbon-segregation, effectively self limiting graphene formation to two layers.