ABSTRACT: Recently, roll-to-roll (R2R) chemical vapor deposition (CVD) processes have been implemented to produce graphene with substrate feed rates ranging from 5-100 mm/min. However, this production rate must increase much further to make graphene a feasible product in semiconductor and materials manufacturing industries. Plasma sources can be applied to increase the graphene deposition rate, and additionally, to decrease energy input. This work will describe the implementation of a radio frequency plasma R2R CVD process to deposit graphene on copper and nickel foils, and carbon fibers. The growth process takes advantage of the high-temperature plasma gas that produces active carbon species to accelerate growth kinetics. Thus, supplemental heating of the substrate is unnecessary when using plasma, in contrast to thermal CVD systems that consume high energy to heat the substrate and to decompose the carbon gas source. In situ temperature measurements of the substrate in the plasma region confirm the plasma’s ability to heat the substrate to the 1200-1500 K range depending on the plasma power. From these real-time temperature measurements, a heat transfer model is developed and validated to determine the substrate temperature profile during R2R graphene growth. The effects of plasma power and web speed on substrate temperature are explored and correlated to graphene quality. The results indicate that graphene growth on Cu foil is most significantly influenced by the in-plasma substrate temperature, whereas growth on Ni foil is controlled by the substrate cooling rate, which is evaluated from the heat transfer model. Furthermore, the plasma environment is characterized by optical emission spectroscopy (OES) to optimize graphene growth and assess the impact of ion bombardment. The OES results suggest that the quality of graphene deposited on Cu foil is enhanced with increased CH emission and decreased emission from O, H, Ar+, C2, and CN. The process characterization techniques aid in controlling and optimizing graphene growth in a large-scale setup, and the talk will conclude with a discussion of plans to bring a similar capability to CNSI, as well as applications of the resulting materials in energy and biosensing technologies.
BIOSKETCH: Timothy S. Fisher (PhD in Mechanical Engineering, 1998, Cornell) was born in Aurora, IL USA. He joined UCLA’s Department of Mechanical & Aerospace Engineering in 2017 after spending 15 years in Purdue’s School of Mechanical Engineering, and several previous years at Vanderbilt University. He is an Adjunct Professor in the International Centre for Materials Science at the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR) and co-directs the JNCASR-Purdue Joint Networked Centre on Nanomaterials for Energy. From 2009 to 2012, he served as a Research Scientist at the Air Force Research Laboratory’s newly formed Thermal Sciences and Materials Branch of the Materials and Manufacturing Directorate. He is active in service to the American Society of Mechanical Engineers through a variety of responsibilities, and is a former Co-Editor of the journal Energy Conversion & Management and currently Specialty Chief Editor for Thermal and Mass Transport of the journal Frontiers in Mechanical Engineering.
Date(s) - May 18, 2018
11:00 am - 12:00 pm