Thermal conductivity of GaAs/Ge nanostructures
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Fitzgerald_Thermal conductivity.pdf
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Author(s)
Jia, Roger Qingfeng
Zeng, Lingping
Chen, Gang
Fitzgerald, Eugene A
Date Issued
June 2017
Journal
Applied Physics Letters
Publisher
American Institute of Physics (AIP)
Citation
Jia, Roger et al. “Thermal Conductivity of GaAs/Ge Nanostructures.” Applied Physics Letters 110, 22 (May 2017): 222105 © 2017 Author(s)
Version
Original manuscript
Abstract
Superlattices are of great interest as platform materials for thermoelectric technology that are capable of directly converting low-grade heat energy into useful electrical power. In this work, the thermal conductivities of GaAs/Ge superlattice nanostructures were investigated systematically in relation to their morphologies and interfaces. Thermal conductivities were measured using ultrafast time-domain thermoreflectance and were found to decrease with increasing interface densities, consistent with past understanding of microscopic phonon transport in the particle regime. The lowest thermal conductivities were observed in (GaAs)[subscript 0.77](Ge₂)[subscript 0.23] alloys, and transmission electron microscopy study reveals phase separation in the alloys. These alloys can be interpreted as fine nanostructures, with length scales comparable to the periods of very thin superlattices. Electrical transport measurements along the film plane direction showed no significant reduction in electrical properties attributable to the interfaces between GaAs and Ge. Our experimental findings help gain fundamental insight into nanoscale thermal transport in superlattices and are also useful for future improvement of thermoelectric performance using nanostructures.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Mechanical Engineering
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1063/1.4984957
