Invited Presentation: Synthesis and Characterization of Graphene Layers (*†)

A variety of methods are being employed in the fabrication of graphene layers. These fabricated layers need to be carefully evaluated and compared to a benchmark represented by the graphene layers that are obtained by mechanical exfoliation of graphite.

Two cases are considered here. One is that of graphene layers obtained by chemical vapor deposition (CVD) on Cu. The other case is that of graphene layers obtained by molecular beam (MB) growth, a form of van der Waals epitaxy. The MB epitaxy approach employs a solid carbon source, similar to that used in molecular beam epitaxy. The MB grown layers are fabricated directly on dielectric substrates. This is an achievement that could enable applications in electronics and optoelectronics.

While Raman spectroscopy is a primary characterization tool, techniques such as scanning tunneling microscopy (STM) and X-ray probes are employed to provide key insights.

The CVD graphene layers are coupled to the Cu substrate by weak van der Waals forces. Surprisingly, our studies reveal that strains that result from coupling to the substrate have significant impact on the quality of the graphene layers.

The van der Waals MB growth of single-layer graphene was demonstrated on h-BN and sapphire substrates.

 

(*) In collaboration with: Sheng Wang, Rui He, Lara Fernandes dos Santos, Liuyan. Zhao, U. Wurstbauer, J. M. García, A. N. Pasupathy, P. Kim, J. Hone, Lei Wang, C. R. Dean, Kenji Watanabe, Takashi Taniguchi, L. N. Pfeiffer, and  A. S. Plaut.

 

(†) Supported by ONR and NSF