2018 Fiscal Year Research-status Report
Engineering directional heat flow in semiconductor nanostructures
| Project/Area Number |
18K14078
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| Research Institution | The University of Tokyo |
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Principal Investigator |
Anufriev Roman 東京大学, 生産技術研究所, 特任助教 (40815875)
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| Project Period (FY) |
2018-04-01 – 2020-03-31
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| Keywords | phononics / nanowires / heat conduction / thermal transport |
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| Outline of Annual Research Achievements |
I have experimentally showed quasi-ballistic heat conduction in silicon nanowires (NWs). I showed that the ballisticity is the strongest in short NWs at low temperatures but weakens as the NW length or temperature is increased. Yet, even at room temperature, quasi-ballistic heat conduction remains visible in short NWs. Moreover, I probes directions and lengths of phonon flights. The experiments and simulations showed that the quasi-ballistic phonon transport in NWs is essentially the Levy walk with short flights between the NW boundaries and long ballistic leaps along the NW. Thus, I concludeed that ballistic heat conduction is present in silicon even at room temperature in sufficiently small nanostructures and may yet improve thermal management in silicon-based microelectronics.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
Due to our previous experience in fabrication and measurements I was able to obtain the results earlier than planned.
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| Strategy for Future Research Activity |
Next year, I plan to switch the system from nanowires to thin membranes. My experiments in the previous year showed that phonon transport is strongly impacted by the nanowires boundaries. Thus, to avoid this effect and study the ballistic phonon transport I decided to try less confined system. I plan to try new fabrication method, based on already pre-suspended nanomembranes, on which I'll deposit metal pads and measure using both time-domain thermoreflectance and Brillouin scattering techniques.
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