title: Length dependent thermal conductivity measurements yield phonon mean free path spectra in nanostructures.
abstract: Thermal conductivity measurements over variable lengths on nanostructures such as nanowires provide important information about the mean free paths (MFPs) of the phonons responsible for heat conduction. However, nearly all of these measurements have been interpreted using an average MFP even though phonons in many crystals possess a broad MFP spectrum. Here, we present a reconstruction method to obtain MFP spectra of nanostructures from variable-length thermal conductivity measurements. Using this method, we investigate recently reported length-dependent thermal conductivity measurements on SiGe alloy nanowires and suspended graphene ribbons. We find that the recent measurements on graphene imply that 70% of the heat in graphene is carried by phonons with MFPs longer than 1 micron.
authors.affiliation: Division of Engineering and Applied Science California Institute of Technology Pasadena, CA 91125.
authors.forename: Hang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Division of Engineering and Applied Science California Institute of Technology Pasadena, CA 91125.
authors.forename: Chengyun
authors.initials: C
authors.lastname: Hua
authors.affiliation: Division of Engineering and Applied Science California Institute of Technology Pasadena, CA 91125.
authors.forename: Ding
authors.initials: D
authors.lastname: Ding
authors.affiliation: Division of Engineering and Applied Science California Institute of Technology Pasadena, CA 91125.
authors.forename: Austin J
authors.initials: AJ
authors.lastname: Minnich