title: Phonon dominated heat conduction normal to Mo/Si multilayers with period below 10 nm.
abstract: Thermal conduction in periodic multilayer composites can be strongly influenced by nonequilibrium electron-phonon scattering for periods shorter than the relevant free paths. Here we argue that two additional mechanisms-quasiballistic phonon transport normal to the metal film and inelastic electron-interface scattering-can also impact conduction in metal/dielectric multilayers with a period below 10 nm. Measurements use the 3ω method with six different bridge widths down to 50 nm to extract the in- and cross-plane effective conductivities of Mo/Si (2.8 nm/4.1 nm) multilayers, yielding 15.4 and 1.2 W/mK, respectively. The cross-plane thermal resistance is lower than can be predicted considering volume and interface scattering but is consistent with a new model built around a film-normal length scale for phonon-electron energy conversion in the metal. We introduce a criterion for the transition from electron to phonon dominated heat conduction in metal films bounded by dielectrics.
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, California 94305, United States.
authors.forename: Zijian
authors.initials: Z
authors.lastname: Li
authors.forename: Si
authors.initials: S
authors.lastname: Tan
authors.forename: Elah
authors.initials: E
authors.lastname: Bozorg-Grayeli
authors.forename: Takashi
authors.initials: T
authors.lastname: Kodama
authors.forename: Mehdi
authors.initials: M
authors.lastname: Asheghi
authors.forename: Gil
authors.initials: G
authors.lastname: Delgado
authors.forename: Matthew
authors.initials: M
authors.lastname: Panzer
authors.forename: Alexander
authors.initials: A
authors.lastname: Pokrovsky
authors.forename: Daniel
authors.initials: D
authors.lastname: Wack
authors.forename: Kenneth E
authors.initials: KE
authors.lastname: Goodson
mesh_terms: D003198:Computer Simulation; D006358:Hot Temperature; D008956:Models, Chemical; D008982:Molybdenum / Q000737:chemistry*; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012825:Silicon / Q000737:chemistry*; D013814:Thermal Conductivity
chemical_list: D008982:Molybdenum; D012825:Silicon