Understanding the origin of heat conduction in thin films -Breakthrough for evaluation of thermal properties of energy- efficient devices (Press Release)
- Release Date
- 11 Jun, 2018
- BL35XU (High Resolution lnelastic Scattering)
June 11, 2018
Japan Synchrotron Radiation Research Institute (JASRI)
The University of Tokyo
Key points
・A challenge of next-generation devices (e.g., solar cells, thermoelectric materials, power devices) is to reduce the amount of energy wasted in the form of unused heat. Thermal properties are inextricably connected to the phonon lifetime at the microscopic level, and, in the present study, the details of the origin of thermal properties, including the mechanism of macroscopic thermal conductivity, were clarified by measuring the lifetime of phonons in a thin film, which mimics a device, on a substrate.
・The research group succeeded in simultaneously measuring the phonon dispersion curve and lifetime in thin films for the first time in the world.
・The technique developed in this study is expected to be leveraged in the determination of the thermal properties of next-generation energy-efficient devices.
The achievements of this study were published online on 7 June 2018 (eastern time, USA) in Physical Review Letters.
The research group led by Hiroshi Uchiyama (research scientist) of JASRI and Sotaro Iwamoto (graduate student) and Junichiro Shiomi (professor) of School of Engineering, The University of Tokyo, succeeded in simultaneous measurements of the phonon dispersion curve and lifetime of an epitaxial film, for the first time in the world, jointly with researchers from National Institute for Materials Science and the University of New South Wales, Australia. Phonons are directly associated with thermal properties such as heat dissipation and conduction. By comparing the obtained data with the results of thermal conductivity measurement and calculated data, the microscopic mechanism of thermal properties in a thin film, which is similar to an actual device environment, was clarified. The measurement technique newly developed in this study facilitates the detailed measurement of phonons in microdevices. The achievements of this study are expected to be applied to the evaluation of the thermal properties of leading-edge energy-efficient/energy creation devices (thermoelectric devices that convert heat into electricity, highly efficient power semiconductor devices with low energy loss, and next-generation solar cells). Reference: |
Fig. 1 (a) Schematic of experimental setup; thin film on substrate and path of X-ray used in the experiment.
(b) Mechanism of heat generation by phonon scattering.
Fig. 2 Phonon dispersion curves (energy dispersion as a function of reciprocal lattice units) in ScN film observed by inelastic X-ray scattering spectroscopy. The phonon lifetime is estimated from the spectral width of the bright areas (phonon linewidth).
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- Understanding the origin of heat conduction in thin films -Breakthrough for evaluation of thermal properties of energy- efficient devices (Press Release)