Bimodal Phonon Scattering in Graphene Grain Boundaries
- Publication date
- 2015
- Publisher
Abstract
Graphene has served as the model
2D system for over a decade, and the effects of grain boundaries (GBs)
on its electrical and mechanical properties are very well investigated.
However, no direct measurement of the correlation between thermal
transport and graphene GBs has been reported. Here, we report a simultaneous
comparison of thermal transport in supported single crystalline graphene
to thermal transport across an individual graphene GB. Our experiments
show that thermal conductance (per unit area) through an isolated
GB can be up to an order of magnitude lower than the theoretically
anticipated values. Our measurements are supported by Boltzmann transport
modeling which uncovers a new bimodal phonon scattering phenomenon
initiated by the GB structure. In this novel scattering mechanism,
boundary roughness scattering dominates the phonon transport in low-mismatch
GBs, while for higher mismatch angles there is an additional resistance
caused by the formation of a disordered region at the GB. Nonequilibrium
molecular dynamics simulations verify that the amount of disorder
in the GB region is the determining factor in impeding thermal transport
across GBs