Low-pressure chemical vapor deposition (LPCVD) is the most efficient method to synthesize large-scale, high-quality graphene for many potential applications such as flexible electronics, solar cells, and separation membranes. The quality of LPCVD is affected by process variables including methane/hydrogen (CH4/H2) ratio, time, pressure, temperature, and cooling rate. The cooling rate has been recognized as one of the most important process variables affecting the amount of carbon source, nucleation, reaction time, and thus the quality of the LPCVD. In this research, we investigate the effect of cooling rate on the quality of graphene synthesize by changing the cooling rate from 0.2℃/s to 3.5℃/s, while the gas feeding time is also varied. A computer-controlled movable platform is built to control the temperature profile and cooling rate of the LPCVD process. Graphene coverage of the growth substrate is measured by Raman mapping. It is found that fast cooling rate leads to decreased carbon source reaction time, which in turn results in higher coverage by monolayer graphene. The temperature-dependent gas feeding time corresponding to different cooling rates can be used to properly supply the carbon source onto the copper surface, leading to a higher graphene coverage. Overall, fast cooling rate and temperature dependent gas feeding time are required to obtain monolayer graphene with high quality.

The Cooling Rate Effect on Graphene Synthesis in Low Pressure Chemical Vapor Deposition

Paper Proceedings: https://asmedigitalcollection.asme.org/MSEC/MSEC2021/volume/85062

2021 International Manufacturing Science and Engineering Conference (MSEC2021)

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