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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-474-8

ISBN Online: 978-1-56700-473-1

International Heat Transfer Conference 16
August, 10-15, 2018, Beijing, China

THERMAL ANALYSIS AND OPTIMIZATION OF GRAPHENE DEPOSITION IN A ROLL-TO-ROLL PLASMA CVD PROCESS

Get access (open in a dialog) DOI: 10.1615/IHTC16.mmp.022647
pages 5661-5668

Abstract

A roll-to-roll plasma chemical vapor deposition system has been designed and built to mass-produce graphene and other nanostructures on a variety of flexible substrates. The temperature of copper foil, a common substrate for graphene film deposition, plays an essential role in controlling the quality and uniformity of graphene at high throughput. A heat transfer model is developed to determine the temperature distribution of the copper substrate during roll-to-roll graphene growth in a plasma. Analytical and numerical fin-type models are derived based on heat transfer principles to study the effects of web speed and plasma power on the copper foil temperature distribution. With knowledge of the gas temperature derived from optical emission spectroscopy, the heat transfer coefficient in the plasma region is estimated by fitting modeled temperature distributions with copper foil temperature measurements using a blackbody analysis from optical emission spectroscopy in the wavelength range 680-850 nm. The convective heat transfer coefficient in the plasma region increases with increased plasma power, whereas it decays exponentially with higher web speed. Therefore, the copper foil temperature increases with increased plasma power at constant web speed due to the higher gas temperature of the plasma. However, the copper foil temperatures decrease, and its maximum value shifts downstream, with increased web speed at constant plasma power. As a result, the quality of graphene on copper foil, measured from Raman spectroscopy, is maximized at higher copper foil temperatures because the growth is driven by the catalytic reaction of methane on the copper surface.