Multilayer thermionic refrigerator and generator

Mahan, G. D.; Sofo, Jorge O.; Bartkowiak, M.

doi:10.1063/1.367255

Cited by 140 publications

(76 citation statements)

References 14 publications

(19 reference statements)

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“…8 There is, however, little to distinguish the underlying thermodynamics of the two types of device, with both achieving reversibility under the same conditions 25 and both being governed by the same "materials parameter." 29,30,37 Under the relaxation-time approximation the electric current in a thermoelectric device may be calculated using the Boltzmann transport equation as…”

Section: A Diffusive Transport Theorymentioning

confidence: 99%

“…The potential for achieving lower barrier heights via the use of semiconductor heterostructures was pointed out by Shakouri and Bowers, 5,6 with Mahan et al 7,8 suggesting multilayers as a means of reducing the phonon heat leaks inherent in the use of solidstate rather than vacuum devices. Successful solid-state thermionic cooling of up to a few degrees has been reported.…”

Section: Introductionmentioning

confidence: 99%

“…The close relationship between thermionic and thermoelectric devices has been analyzed by a number of authors. 8,[28][29][30] In this paper, this comparison is extended to similarities between the dependence of the electronic efficiencies of these devices on the details of the electron energy spectrum.…”

Section: Introductionmentioning

confidence: 99%

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Electronic efficiency in nanostructured thermionic and thermoelectric devices

et al. 2005

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Advances in solid-state device design now allow the spectrum of transmitted electrons in thermionic and thermoelectric devices to be engineered in ways that were not previously possible. Here we show that the shape of the electron energy spectrum in these devices has a significant impact on their performance. We distinguish between traditional thermionic devices where electron momentum is filtered in the direction of transport only and a second type, in which the electron filtering occurs according to total electron momentum. Such "total momentum filtered" thermionic devices could potentially be implemented in, for example, quantum dot superlattices. It is shown that whilst total momentum filtered thermionic devices may achieve an efficiency equal to the Carnot value, traditional thermionic devices are limited to an efficiency below this. Our second main result is that the electronic efficiency of a device is not only improved by reducing the width of the transmission filter as has previously been shown, but also strongly depends on whether the transmission probability rises sharply from zero to full transmission. The benefit of increasing efficiency through a sharply rising transmission probability is that it can be achieved without sacrificing device power, in contrast to the use of a narrow transmission filter which can greatly reduce power. We show that devices that have a sharply rising transmission probability significantly outperform those that do not and that such transmission probabilities may be achieved with practical single and multibarrier devices. We discuss how the shape of the electron energy spectrum will also have an effect on the electronic efficiency of thermoelectric devices due to mathematical equivalences in the ballistic and diffusive formalisms. Finally, we present an experimental measure that might be used to provide an indication of the nature of the electron energy spectrum and the electronic efficiency of a ballistic device.

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Section: A Diffusive Transport Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electronic efficiency in nanostructured thermionic and thermoelectric devices

et al. 2005

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“…Mahan et al later proposed multilayer structures as a way of reducing phonon heat leaks inherent in the use of solid-state rather than vacuum-based devices, thus improving efficiency [7], [8]. Successful solidstate thermionic cooling has been reported by Shakouri et al using a single-barrier InGaAsP based structure [9] and by LaBounty et al using a 25-barrier InGaAsP based multilayer system [10].…”

Section: Introductionmentioning

confidence: 97%

The Electron Energy Spectrum and Thermionic Device Efficiency

O'Dwyer

Humphrey

Lewis

et al.

Conference on Optoelectronic and Microelectronic Materials and Devices, 2004.

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Abstract-The influence of the electron energy spectrum of solid-state thermionic devices on electronic efficiency is analyzed. Calculations are performed on both single and multibarrier GaAs/AlGaAs and InGaAs/InAlAs systems. Analysis reveals a wide barrier is desirable for single-barrier thermionic devices due to the associated sharpness in the electron energy spectrum. It is also shown that high electronic efficiency may be achieved in multibarrier thermionic devices consisting of thin barriers, which would separately give low efficiency, but together can be arranged to produce a desirable electron energy spectrum.

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“…The main challenges in designing a practical thermionic device are to maximise the thermal emission of electrons and to minimise the heat backflow due to phonons. Mahan et al [4] proposed using a multibarrier system, reasoning that using N barriers identical to a single barrier would reduce the temperature gradient across each barrier to ∼ ΔT/N, effectively reducing the back-flow by a factor of N . A second advantage of using a multibarrier system stems from experimental work carried out on the thermal conduction of superlattices as compared to bulk materials [5].…”

Section: Introductionmentioning

confidence: 99%

Electrical and Thermal Characteristics of Multilayer Thermionic Power Devices

Lough

Lewis

Zhang

Conference on Optoelectronic and Microelectronic Materials and Devices, 2004.

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Abstract-Electron thermal transport in semiconductor thermionic devices is investigated numerically. The efficiency of thermionic devices is dramatically reduced by the conduction heat current, ΔT /R th . One approach to reduce the thermal conductivity is to use layered structures where interface scattering can increase the thermal resistivity. It is found that the temperature gradient across the devices can be increased by a factor of 2 in the presence of phonon scattering. The device is more efficient at elevated temperature.

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Multilayer thermionic refrigerator and generator

Cited by 140 publications

References 14 publications

Electronic efficiency in nanostructured thermionic and thermoelectric devices

Electronic efficiency in nanostructured thermionic and thermoelectric devices

The Electron Energy Spectrum and Thermionic Device Efficiency

Electrical and Thermal Characteristics of Multilayer Thermionic Power Devices

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