Near Room Temperature Graphene-Edge Growth with Diluted Methane Cvd and Molten Gallium Catalyst
Jun-ichi Fujita1,3*, Takaki Hiyama1,3, Ayaka Hirukawa1,3, Takahiro Kondo2,3, Junji Nakamura2,3, Shin-ichi Ito2,3, Masaki Takeguchi4, Woei Wu Pai5
1Institute of Applied Physics, University of Tsukuba, Tsukuba, Japan
2Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Japan
3Tsukuba Research Center for Interdisciplinary Materials Science, University of Tsukuba, Tsukuba, Japan
4National Institute for Materials Science, Tsukuba, Japan
5Center for Condensed Matter Sciences and Department of Physics, National Taiwan University, Taipei, Taiwan
* presenting author:Jun-ichi Fujita,
Reduction of the growth temperature of graphene is highly desirable for the integration of the graphene-based electronics. Here, we have demonstrated that graphene edge growth can proceed near room temperature using diluted methane CVD with the catalyst of molten gallium. We show that pre-existing graphene nuclei islands are essential for low-temperature graphene synthesis through carbon attachment to the island edge. Low-temperature graphene grows at the edge of graphene islands was confirmed by isotope labeling with 12C- and 13C-methane. An unexpectedly low apparent barrier of ~0.16 eV at <300 °C for graphene growth rate was observed, owing to the preferable methane absorption in molten Ga at a lower temperature. The fluidity of molten gallium also contributes to easier transport and production of atomic carbon. The combination of methane absorption, methane dehydrogenation, and effective carbon transport through the molten gallium to graphene island edges underlie the driving forces for the near room temperature graphene CVD. We also demonstrated graphene CVD on polycarbonate by transferring and seeding the essential graphene nuclei across the solid-liquid phase transition of gallium. These results in successful graphene growth on a plastic substrate at 100 °C, thus representing a significant step toward the integration of graphene in plastic electronic devices.

Keywords: graphene, low-temperature, edge-growth, gallium, catalysis