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A new method for heat guidance and focusing in solid--- Associate Professor Masahiro Nomura

Institute of Industrial Science

05/19/2017

Points:
≫Researchers showed a method to control the directionality of heat that has been thought to diffuse without a certain direction in solid.
≫Researchers achieved heat focusing into a spot of a few hundred nanometers for the first time.
≫A new structural design is provided to contribute to solving the problem of heat dissipation in semiconductor chips and realize more advanced heat management.

Summary:
In a new study published in Nature Communications, a research group led by associate professor Masahiro Nomura, Institute of Industrial Science, the University Tokyo, shows a method to control the directionality of ballistic phonon transport using silicon membranes with arrays of holes and to focus heat into a spot of a few hundred nanometres for the first time.
It has been a challenge to guide heat into a certain direction because of its diffusive characteristic in solid. Therefore, realization of directional heat flow will enable more advanced heat flux management.
In this study, Nomura et al. show a method to control the directionality of ballistic phonon transport using silicon membranes with arrays of holes. First, they demonstrate that the arrays of holes form fluxes of phonons oriented in the same direction. Next, they use these nanostructures as directional sources of ballistic phonons and couple the emitted phonons into nanowires. Finally, they introduce thermal lens nanostructures, in which the emitted phonons converge at the focal point, thus focusing heat into a spot of a few hundred nanometres. These results motivate the concept of ray-like heat flux manipulations at the nanoscale.
They provide a new option for heat flux control technique and shed light on advanced heat management for highly efficient heat dissipation in such devices as semiconductor chips.

Journal Article:
R. Anufriev, A. Ramiere, J. Maire, and M. Nomura, "Heat guiding and focusing using ballistic phonon transport in phononic nanostructures", Nature Communications, 8 15505 (2017), doi:10.1038/ncomms15505

Article link https://www.nature.com/articles/ncomms15505

Press Release:
Article link https://www.iis.u-tokyo.ac.jp/ja/news/2707/

Contact:
Masahiro Nomura, Associate Professor
Institute of Industrial Science, The University of Tokyo
TEL: +81 3 5452-3525

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