Modifying Surface Energy of Graphene via Plasma-Based
Chemical Functionalization to Tune Thermal and Electrical Transport
at Metal Interfaces
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Abstract
The high mobility exhibited by both
supported and suspended graphene, as well as its large in-plane thermal
conductivity, has generated much excitement across a variety of applications.
As exciting as these properties are, one of the principal issues inhibiting
the development of graphene technologies pertains to difficulties
in engineering high-quality metal contacts on graphene. As device
dimensions decrease, the thermal and electrical resistance at the
metal/graphene interface plays a dominant role in degrading overall
performance. Here we demonstrate the use of a low energy, electron-beam
plasma to functionalize graphene with oxygen, fluorine, and nitrogen
groups, as a method to tune the thermal and electrical transport properties
across gold-single layer graphene (Au/SLG) interfaces. We find that
while oxygen and nitrogen groups improve the thermal boundary conductance
(<i>h</i><sub>K</sub>) at the interface, their presence
impairs electrical transport leading to increased contact resistance
(ρ<sub>C</sub>). Conversely, functionalization with fluorine
has no impact on <i>h</i><sub>K</sub>, yet ρ<sub>C</sub> decreases with increasing coverage densities. These findings indicate
exciting possibilities using plasma-based chemical functionalization
to tailor the thermal and electrical transport properties of metal/2D
material contacts