Rigorous calculation of the Seebeck coefficient and mobility of thermoelectric materials

Ramu, Ashok T.; Cassels, Laura E.; Hackman, Nathan H.; Lü, Hong; Zide, Joshua M. O.; Bowers, John E.

doi:10.1063/1.3366712

Cited by 50 publications

(36 citation statements)

References 17 publications

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“…1(b) shows that the peak power factors appear at 0.35% ScAs and 0.05% ErAs, and the value of the former is about 38% of the latter. [14]. The power factor of ScAs:InGaAs nanocomposites is only slightly enhanced with respect to that of Si:InGaAs below the carrier concentration level of 1.6 Â 10 18 cm À 3 .…”

Section: Methodsmentioning

confidence: 88%

Properties of molecular beam epitaxially grown ScAs:InGaAs and ErAs:InGaAs nanocomposites for thermoelectricapplications

Liu¹,

Ramu²,

Bowers³

et al. 2011

Journal of Crystal Growth

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a b s t r a c tWe report the molecular beam epitaxy (MBE) growth and the comparative systematic study of the electrical and thermoelectric characterizations of ScAs:In 0.53 Ga 0.47 As and ErAs:In 0.53 Ga 0.47 As nanocomposites. The peak room-temperature power factor of ScAs:InGaAs is 38% comparing to that of ErAs:InGaAs. The carrier concentration change of the nanocomposites versus the ScAs and ErAs incorporation levels below 2.2% is explained as due to the formation of nanoparticles with different sizes and densities. The carrier concentration difference between the two types of nanocomposites at the same incorporation level of ScAs and ErAs is explained by the size difference between the ScAs and ErAs nanoparticles.

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Section: Methodsmentioning

confidence: 88%

Properties of molecular beam epitaxially grown ScAs:InGaAs and ErAs:InGaAs nanocomposites for thermoelectricapplications

Liu¹,

Ramu²,

Bowers³

et al. 2011

Journal of Crystal Growth

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“…The lower thermal conductivities seen in In x Ga 1Àx N and In x Al 1Àx N are driven primarily by the large indium atoms since phonon mass defect scattering is a function of both atomic weight squared and atomic radius squared, as can be seen in Eqs. (30) and (31). The relatively small aluminum atoms provide less mass defect scattering and thus less reduction of thermal conductivity than the larger indium atoms.…”

Section: Alganmentioning

confidence: 99%

“…If this mechanism becomes the dominant scattering mechanism, then this approximation is no longer valid and either an iterative approach 30 …”

Section: Electron Transport Modelmentioning

confidence: 99%

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Sztein

Haberstroh

Bowers

et al. 2013

Journal of Applied Physics

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The thermoelectric properties of III-nitride materials are of interest due to their potential use for high temperature power generation applications and the increasing commercial importance of the material system; however, the very large parameter space of different alloy compositions, carrier densities, and range of operating temperatures makes a complete experimental exploration of this material system difficult. In order to predict thermoelectric performances and identify the most promising compositions and carrier densities, the thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN are modeled. The Boltzmann transport equation is used to calculate the Seebeck coefficient, electrical conductivity, and the electron component of thermal conductivity. Scattering mechanisms considered for electronic properties include ionized impurity, alloy potential, polar optical phonon, deformation potential, piezoelectric, and charged dislocation scattering. The Callaway model is used to calculate the phonon component of thermal conductivity with Normal, Umklapp, mass defect, and dislocation scattering mechanisms included. Thermal and electrical results are combined to calculate ZT values. InxGa1−xN is identified as the most promising of the three ternary alloys investigated, with a calculated ZT of 0.85 at 1200 K for In0.1Ga0.9N at an optimized carrier density. AlxGa1−xN is predicted to have a ZT of 0.57 at 1200 K under optimized composition and carrier density. InxAl1−xN is predicted to have a ZT of 0.33 at 1200 K at optimized composition and carrier density. Calculated Seebeck coefficients, electrical conductivities, thermal conductivities, and ZTs are compared with experimental data where such data are available.

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“…20 More details about the BTE solution can be found in Ref. 19. However, even this accuracy (10%) is too low for a thermometric reference.…”

Section: Sample Preparation and Metrologymentioning

confidence: 99%

“…Second, the Seebeck coefficient of III-V compound semiconductors can be quite accurately calculated by numerical solution of the Boltzmann transport equation (BTE) beyond the relaxation time approximation (RTA). 19 Optical-mode phonon in-scattering, which cannot be described by the RTA, is included by an extension of the iterative method first developed by Rode. 26 This is significant at high temperatures due to the increased occupation of optical modes.…”

Section: Sample Preparation and Metrologymentioning

confidence: 99%

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material

Ramu

Mages

Zhang

et al. 2012

Review of Scientific Instruments

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The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.

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Rigorous calculation of the Seebeck coefficient and mobility of thermoelectric materials

Cited by 50 publications

References 17 publications

Properties of molecular beam epitaxially grown ScAs:InGaAs and ErAs:InGaAs nanocomposites for thermoelectricapplications

Properties of molecular beam epitaxially grown ScAs:InGaAs and ErAs:InGaAs nanocomposites for thermoelectricapplications

Calculated thermoelectric properties of InxGa1−xN, InxAl1−xN, and AlxGa1−xN

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material

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