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High-frequency phonons drive large phonon-drag thermopower in semiconductors at high carrier density

Li, C and Protik, NH and Ravichandran, NK and Broido, D (2023) High-frequency phonons drive large phonon-drag thermopower in semiconductors at high carrier density. In: Physical Review B, 107 (8).

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Official URL: https://10.1103/PhysRevB.107.L081202


It has been well established that (i) the thermopower of semiconductors can be enhanced through a phenomenon known as the drag effect, and (ii) the drag enhancement involves only low-frequency acoustic phonons and benefits from low electron densities and low temperatures. Using first-principles calculations we show that large drag enhancements to the thermopower are possible at high carrier density even at room temperature and arise from high-frequency acoustic phonons. A fascinating example is cubic boron arsenide (BAs) for which the calculated room temperature drag enhancement of the thermopower exceeds an order of magnitude at a high hole density of 1021cm-3. This remarkable behavior stems from the simultaneously weak phonon-phonon and phonon-hole scattering of the high-frequency phonons in BAs that become drag active at high carrier densities through electron-phonon interactions. This work advances our understanding of coupled electron-phonon nanoscale transport and introduces an unexpected paradigm for achieving large thermopowers. © 2023 American Physical Society.

Item Type: Journal Article
Publication: Physical Review B
Publisher: American Physical Society
Additional Information: The copyright of this article belongs to American Physical Society.
Keywords: Arsenic compounds; Drag; III-V semiconductors; Thermoelectric power; Acoustic phonons; Acoustic-phonons; Drag effects; Drag enhancement; First principle calculations; High frequency phonons; Low frequency acoustic; Lower electron density; Lows-temperatures; Phonon drag; Carrier concentration
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 10 Mar 2023 10:35
Last Modified: 10 Mar 2023 10:35
URI: https://eprints.iisc.ac.in/id/eprint/80911

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