dc.contributor.author |
Hoffmann, Eric A., 1982- |
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dc.date.accessioned |
2010-07-28T23:32:25Z |
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dc.date.available |
2010-07-28T23:32:25Z |
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dc.date.issued |
2009-12 |
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dc.identifier.uri |
http://hdl.handle.net/1794/10552 |
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dc.description |
xi, 193 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. |
en_US |
dc.description.abstract |
State of the art semiconductor materials engineering provides the possibility to fabricate devices on the lower end of the mesoscopic scale and confine only a handful of electrons to a region of space. When the thermal energy is reduced below the energetic quantum level spacing, the confined electrons assume energy levels akin to the core-shell structure of natural atoms. Such "artificial atoms", also known as quantum dots, can be loaded with electrons, one-by-one, and subsequently unloaded using source and drain electrical contacts. As such, quantum dots are uniquely tunable platforms for performing quantum transport and quantum control experiments. Voltage-biased electron transport through quantum dots has been studied extensively. Far less attention has been given to thermoelectric effects in quantum dots, that is, electron transport induced by a temperature gradient.
This dissertation focuses on the efficiency of direct thermal-to-electric energy conversion in InAs/InP quantum dots embedded in nanowires. The efficiency of thermoelectric heat engines is bounded by the same maximum efficiency as cyclic heat engines; namely, by Carnot efficiency. The efficiency of bulk thermoelectric materials suffers from their inability to transport charge carriers selectively based on energy. Owing to their three-dimensional momentum quantization, quantum dots operate as electron energy filters--a property which can be harnessed to minimize entropy production and therefore maximize efficiency. This research was motivated by the possibility to realize experimentally a thermodynamic heat engine operating with near-Carnot efficiency using the unique behavior of quantum dots.
To this end, a microscopic heating scheme for the application of a temperature difference across a quantum dot was developed in conjunction with a novel quantum-dot thermometry technique used for quantifying the magnitude of the applied temperature difference. While pursuing high-efficiency thermoelectric performance, many mesoscopic thermoelectric effects were observed and studied, including Coulomb-blockade thermovoltage oscillations, thermoelectric power generation, and strong nonlinear behavior. In the end, a quantum-dot-based thermoelectric heat engine was achieved and demonstrated an electronic efficiency of up to 95% Carnot efficiency. |
en_US |
dc.description.sponsorship |
Committee in charge: Stephen Kevan, Chairperson, Physics;
Heiner Linke, Member, Physics;
Roger Haydock, Member, Physics;
Stephen Hsu, Member, Physics;
David Johnson, Outside Member, Chemistry |
en_US |
dc.language.iso |
en_US |
en_US |
dc.publisher |
University of Oregon |
en_US |
dc.relation.ispartofseries |
University of Oregon theses, Dept. of Physics, Ph. D., 2009; |
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dc.subject |
Thermoelectric efficiency |
en_US |
dc.subject |
Quantum dots |
en_US |
dc.subject |
Nanowires |
en_US |
dc.subject |
Indium arsenide |
en_US |
dc.subject |
Indium phosphide |
en_US |
dc.subject |
Solid state physics |
en_US |
dc.subject |
Materials science |
en_US |
dc.title |
The thermoelectric efficiency of quantum dots in indium arsenide/indium phosphide nanowires |
en_US |
dc.type |
Thesis |
en_US |