In Situ Graphene Growth Dynamics on Polycrystalline Catalyst Foils

Ashwin Shahani

Assistant Professor

shahani@umich.edu

2034 H.H. Dow

T: (734) 764-5648

Bio

Publications


Robert S Weatherup, Ashwin J Shahani, Zhu-Jun Wang, Ken Mingard, Andrew J Pollard, Marc-Georg Willinger, Robert Schloegl, Peter W Voorhees, and Stephan Hofmann (2016)

Nano Letters, 16(10):6196-6206.

The dynamics of graphene growth on polycrystalline Pt foils during chemical vapor deposition (CVD) arelaveitigated using in situ scanning electron microscopy and complementary structural characterization of the catalyst with electron backscatter diffraction. A general growth model outlined that considers precursor dissociation, mass transport, and attachment to the edge of a growing domain. We thereby analyze graphene growth dynamics at different length scales and reveal that the rate -limiting `step varies throughout the process and across different regions of the catalyst surface, including different facets of an individual. graphene domain. The facets, that define the domain shapes lie normal to Slow growth directions, which are determined, by the. interfacial mobility when attachment to domain edges is rate limiting, as well as anisotropy in surface diffusion as diffusion becomes rate limiting. Our observations and analysis thus reveal that the structure of CVD graphene films is intimately linked to that of the underlying polycrystalline catalyst, with both interfacial mobility and diffusional anisotropy depending on the presence of step edges and grain boundaries. The growth model developed serves as a general framework for understanding and optimizing the growth of 2D materials on polycrystalline catalysts.

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