Methods To Synthesize Large Area Graphene Films
In this work, we are exploring methods to synthesize large area graphene films directly on dielectric substrates without a transfer process. The method utilizes thin films of Cu and Ni on dielectric substrates along with polymers as a solid carbon source. Another technique utilizes metals with trace carbon as carbon source for the formation of graphene. The method has produced wafer scale continuous graphene films without a transfer process. Additional work in the characterization of the growth process is on going.
Carbon Nanotube Thermal Interface Materials
In this work, we are developing growth and bonding methods to create high performance thermal interface materials using vertically aligned carbon nanotubes. The CNTs are grown on metal foils (Cu, Al) and metalized for attachment to electronic devices. The compliance of the CNT foils are advantageous for limiting thermal stresses on the electronic die. Methods to improve bonding techniques and to reduce thermal resistance are being explored. (collaborators: Cola, Fisher, Raytheon)
Mechanical Deformation of Vertically Aligned Carbon Nanotubes
In this work, we are studying the mechanical properties and deformation response of vertically aligned carbon nanotubes and relating the behavior to structural morphology. Through a collaboration with the Greer group at Cal Tech, we have shown through in-situ nanoindentation studies in SEM that the morphology of compliant CNT arrays plays a large role in their deformation and elastic response.
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Applying a coating at the top of the array increases the stiffness and changes the deformation response of the CNTs: a) uncoated array, b) 100nm Al coating, c) 500 nm Al coating, d) 1000 nm Al coating.