When heat goes astray -- non-local heating in a semiconductor
Mahmoud Elhajhasan, Elena Trukhan, Katharina Dudde, Guillaume Würsch, Jana Lierath + 6 more
TLDR
This paper reveals non-local heating in semiconductors, challenging the assumption of heat locality and Fourier's law due to ballistic phonon transport.
Key contributions
- Discovers non-local heating in semiconductors, challenging the heat locality paradigm.
- Shows this non-local heating contradicts Fourier's law on micrometer scales.
- Employs laser heating and Raman thermometry on structured membranes to map temperatures.
- Attributes significant non-local heating to ballistic phonon transport at high temperatures.
Why it matters
This research fundamentally challenges current assumptions about heat transport in semiconductors, revealing non-local heating effects. This has significant implications for designing more efficient and durable semiconductor devices by improving thermal management strategies.
Original Abstract
Heating of semiconductor devices limits their performance and lifetime, which must be addressed by thermal management starting at the heat source. It is a common assumption that the heat source and the resulting heat spot locally coincide, if their size exceeds the mean free paths of the main heat carriers, the phonons. We show that this paradigm of heat locality breaks down on length scales spanning several micrometers. As a consequence, non-local heating occurs in contradiction to Fourier's law. Therefore, we heat laterally structured semiconductor membranes that feature a rising number of interfaces with a well-focussed laser and map-out lattice temperatures by Raman thermometry. Remarkably, the non-local heating can exceed the laser-induced local heating, which we attribute to ballistic phonon transport far above cryogenic temperatures.
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