Observation and manipulation of the wave nature of phonon thermal transport through superlattices
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2016
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| Online Access: | http://hdl.handle.net/1721.1/101535 |
| _version_ | 1826204435330629632 |
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| author | Luckyanova, Maria N. (Maria Nickolayevna) |
| author2 | Gang Chen. |
| author_facet | Gang Chen. Luckyanova, Maria N. (Maria Nickolayevna) |
| author_sort | Luckyanova, Maria N. (Maria Nickolayevna) |
| collection | MIT |
| description | Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015. |
| first_indexed | 2024-09-23T12:55:00Z |
| format | Thesis |
| id | mit-1721.1/101535 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T12:55:00Z |
| publishDate | 2016 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1015352019-04-10T07:59:14Z Observation and manipulation of the wave nature of phonon thermal transport through superlattices Luckyanova, Maria N. (Maria Nickolayevna) Gang Chen. Massachusetts Institute of Technology. Department of Mechanical Engineering. Massachusetts Institute of Technology. Department of Mechanical Engineering. Mechanical Engineering. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2015. Cataloged from PDF version of thesis. Includes bibliographical references (pages 101-130). As the scale of electronic, photonic, and energy harvesting devices has shrunk, the importance of understanding nanoscale thermal transport has grown. In this thesis, we investigate thermal transport through superlattices (SLs), periodic layers of thin films, to better understand thermal conduction at these small scales. The classical picture of nanoscale thermal transport invokes a picture of diffusive scattering of phonons, or lattice vibrations, at the interfaces and boundaries in structures. This picture has been used to explain experimental thermal transport results for a wide variety of nanostructures. Despite the omnipresence of this particle-transport picture of phonon heat conduction, the community has continuously sought an experimental demonstration of the wave regime of thermal transport in nanostructures. In this thesis, we report the first experimental observations of the regimes of coherent phonon transport and phonon localization in thermal conduction through nanostructures. First, in order to better understand thermal transport through SLs, we present measurements of anisotropic thermal conductivity in the same GaAs/AlAs SLs using two different optical techniques, time-domain thermoreflectance (TDTR) for cross-plane measurements, and transient thermal grating (TTG) for in-plane measurements. The results of this study lend insight into the role of interface scattering, previously understood to be the dominant scattering mechanism in these structures, in SLs. The experimentally measured thermal conductivities are compared to results from first principles simulations, and the agreement between the two helps to validate atomistic simulation techniques of transport through SLs. The role of coherent phonon transport is explored by using the TDTR technique to measure the thermal conductivities of SLs with the same period thicknesses but varying numbers of periods. This experimental approach is a departure from traditional studies of SLs where period thicknesses are varied while the SL is grown to be thermally thick. This shift in the experimental paradigm allows us to explore previously elusive phenomena in nanoscale thermal transport. Combined with first principles and Green's functions simulations, the results of these experiments are the first experimental observation of coherent phonon transport through SLs. Finally, experiments on GaAs/AlAs SLs with varying concentrations of ErAs nanodots at the interfaces show the ability to destroy this phonon coherence. The thermal conductivities of such SLs with constant period thicknesses and varying numbers of periods show an overall reduction in thermal conductivity with increasing ErAs concentration. In addition, at low temperatures samples with ErAs at the interfaces show a maximum in thermal conductivity with shorter sample length and then a drop-off for longer samples. These results are signatures of phonon localization, a previously unobserved thermal transport phenomenon. by Maria N. Luckyanova. Ph. D. 2016-03-03T21:07:20Z 2016-03-03T21:07:20Z 2015 2015 Thesis http://hdl.handle.net/1721.1/101535 940559654 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 130 pages application/pdf Massachusetts Institute of Technology |
| spellingShingle | Mechanical Engineering. Luckyanova, Maria N. (Maria Nickolayevna) Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title | Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title_full | Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title_fullStr | Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title_full_unstemmed | Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title_short | Observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| title_sort | observation and manipulation of the wave nature of phonon thermal transport through superlattices |
| topic | Mechanical Engineering. |
| url | http://hdl.handle.net/1721.1/101535 |
| work_keys_str_mv | AT luckyanovamarianmarianickolayevna observationandmanipulationofthewavenatureofphononthermaltransportthroughsuperlattices |