title: Ballistic to diffusive crossover of heat flow in graphene ribbons.
abstract: Heat flow in nanomaterials is an important area of study, with both fundamental and technological implications. However, little is known about heat flow in two-dimensional devices or interconnects with dimensions comparable to the phonon mean free path. Here we find that short, quarter-micron graphene samples reach ~35% of the ballistic thermal conductance limit up to room temperature, enabled by the relatively large phonon mean free path (~100 nm) in substrate-supported graphene. In contrast, patterning similar samples into nanoribbons leads to a diffusive heat-flow regime that is controlled by ribbon width and edge disorder. In the edge-controlled regime, the graphene nanoribbon thermal conductivity scales with width approximately as ~W(1.8)(0.3), being about 100 W m(-1) K(-1) in 65-nm-wide graphene nanoribbons, at room temperature. These results show how manipulation of two-dimensional device dimensions and edges can be used to achieve full control of their heat-carrying properties, approaching fundamentally limited upper or lower bounds.
authors.affiliation: Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Myung-Ho
authors.initials: MH
authors.lastname: Bae
authors.forename: Zuanyi
authors.initials: Z
authors.lastname: Li
authors.forename: Zlatan
authors.initials: Z
authors.lastname: Aksamija
authors.forename: Pierre N
authors.initials: PN
authors.lastname: Martin
authors.forename: Feng
authors.initials: F
authors.lastname: Xiong
authors.forename: Zhun-Yong
authors.initials: ZY
authors.lastname: Ong
authors.forename: Irena
authors.initials: I
authors.lastname: Knezevic
authors.forename: Eric
authors.initials: E
authors.lastname: Pop