Effect of the Flow Regime on Graphene Growth
Ya-Ping Hsieh1, Ching-Hua Shih1*, Yi-Jing Chiu1, Mario Hofmann2
1Graduate Institute of Opto-Mechatronics, National Chung Cheng University and Advanced Institute of Manufacturing with High-Tech Innovations, Taiwan
2Department of Material Science and Engineering, National Cheng Kung University, Taiwan
* presenting author:Ching-Hua Shih, email:abcd2183@hotmail.com
Graphene is a novel 2D material with significant promise for flexible electronics, interconnects, and 3D devices. The most pressing issue for the application of graphene is the scalable production of high quality material. We have recently developed a novel approach to increase the throughput of graphene CVD synthesis. By using closely stacked copper foil substrates, the amount of graphene grown in one batch can be enhanced twenty-fold.

The adjustment of the distance between copper foils allows us to widely tune the fluid dynamical conditions of the graphene growth process. While we observe free flow conditions for large gap sizes, a transition to the molecular flow regime was identified when the gap size is below the mean free path.

By exploring the graphene growth rate we are able to extract the diffusion coefficient for the carbon precursor for each flow condition. The diffusion coefficient was found to decrease with gap size in agreement with the Knudsen condition.

Our analysis of the graphene quality, as quantified by spectroscopic and electrical transport measurements, indicates the importance of a transport-limited growth process to achieve high quality and uniform graphene growth.

Keywords: graphene