Phonon Dominated Heat Conduction Normal to Mo/Si Multilayers with Period below 10 nm
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- 作者：Zijian Li ; Si Tan ; Elah Bozorg-Grayeli ; Takashi Kodama ; Mehdi Asheghi ; Gil Delgado ; Matthew Panzer ; Alexander Pokrovsky ; Daniel Wack ; Kenneth E. Goodson
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：June 13, 2012
- 年：2012
- 卷：12
- 期：6
- 页码：3121-3126
- 全文大小：343K
- 年卷期：v.12,no.6(June 13, 2012)
- ISSN：1530-6992
文摘
Thermal conduction in periodic multilayer composites can be strongly influenced by nonequilibrium electron鈥損honon scattering for periods shorter than the relevant free paths. Here we argue that two additional mechanisms鈥攓uasiballistic phonon transport normal to the metal film and inelastic electron-interface scattering鈥攃an also impact conduction in metal/dielectric multilayers with a period below 10 nm. Measurements use the 3蠅 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鈥揺lectron 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.