Power Factor Enhancement by Modulation Doping in Bulk Nanocomposites

Zebarjadi, Mona; Joshi, Giri; Zhu, Gaohua; Yu, Bo; Minnich, Austin J.; Lan, Yucheng; Wang, Xiaowei; Dresselhaus, M. S.; Ren, Zhifeng; Chen, Gang

doi:10.1021/nl201206d

Cited by 481 publications

(358 citation statements)

References 35 publications

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“…Note that a relatively small change in the Seebeck coefficient between direct doping and modulation doping was also observed experimentally in Ref. [2]. As a result of the superior conductivity, the thermoelectric power factor shown in Fig.…”

Section: Resultssupporting

confidence: 77%

“…In an earlier work we compared the phonon-limited to the phonon plus IIS thermoelectric power factor in Si nanowires (NWs) and demonstrated that both the power factor and ZT could be more than a factor of ~3x lower in the presence of IIS [1]. Thus, modulation doping has been suggested as a possible way to achieve the required high carrier densities, but without the detrimental effects of the ionized dopants in the channel [2]. Indeed, several experimental works indicated that thermoelectric performance modulation over orders of magnitude can be achieved using modulation doping techniques, but in all cases the improvement was only modest [2,3,4,5,6,7,8].…”

Section: Introductionmentioning

confidence: 99%

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Use of Field-Effect Density Modulation to Increase ZT for Si Nanowires: A Simulation Study

Neophytou

Karamitaheri

Kosina

2014

Journal of Elec Materi

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Modulation doping is a promising way to increase the electronic conductivity of thermoelectric materials and achieve high ZT figure of merit. In this work we provide a qualitative and quantitative comparison of the thermoelectric performance of a fieldeffect density modulated Si nanowire channel of diameter D=12nm versus its doped counterpart. We employ self-consistent atomistic tight-binding simulations coupled to the Boltzmann transport equation. We describe the simulation model, and show that as a result of a large improvement in the electrical conductivity, gating, rather than doping, can provide improvements on the thermoelectric power factor larger than 3x. Despite the large increase in the electronic part of the thermal conductivity, the total thermal conductivity is still dominated by phonons. Thus, a ZT figure of merit more than 3x higher can be achieved in the gated channel compared to the doped channel as well. Finally, we show that similar to the case of doped channels, the power factor peak is obtained when the Fermi level resides ~kBT below the band edge.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Use of Field-Effect Density Modulation to Increase ZT for Si Nanowires: A Simulation Study

Neophytou

Karamitaheri

Kosina

2014

Journal of Elec Materi

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“…Potential ways to improve the power factor are through increasing the Seebeck coefficient (S) via band modification 4 or engineering 5 , energy barrier filtering [6][7][8] , additional carrier pocket 9 , and resonant states 10 , or enhancing the mobility such as modulation doping 11 . Among these possibilities, resonant states and additional carrier pockets have led to net increased ZT values via the power factor enhancements 9,10 .…”

Section: Broader Contextmentioning

confidence: 99%

Enhancement of thermoelectric figure-of-merit by resonant states of aluminium doping in lead selenide

Zhang

Wang

Liu

et al. 2012

Energy Environ. Sci.

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408

252

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By adding aluminium (Al) into lead selenide (PbSe), we successfully prepared n-type PbSe thermoelectric materials with a figure-of-merit (ZT) of 1.3 at 850 K. Such high ZT is achieved by a combination of high Seebeck coefficient caused by very possibly the resonant states in the conduction band created by Al dopant and low thermal conductivity from nanosized phonon scattering centers. Broader contextThermoelectric devices directly convert heat to electricity, thus they are important for harvesting natural heat as well as waste heat. For efficient devices, high figure-of-merit (ZT) materials are desired. We report here n-type lead selenide (PbSe) thermoelectric materials with ZT of 1.3 at 850 K. These materials are prepared by adding aluminium (Al) in PbSe during ball milling and hot pressing. Al, as a dopant in PbSe, possibly creates resonant states in the conduction band and causes increase in the local density of states (DOS) near the Fermi level. As a result, the Seebeck coefficients of Al added PbSe samples are about 40~100% higher than the predicted values by the simple parabolic band model and about 40% higher than the Cl-doped reference PbSe sample without resonant states. Furthermore, using ball milling and hot pressing technique, the structure of our samples contains features such as Pb depleted discs, small grains, and ~10 nm subgrains that are effective for phonon scattering, and result in a much lower lattice thermal conductivity of 0.6~0.7 Wm

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“…Many efforts have been made to further increase the ZT of Bi 2 Te 3 or its alloys in nanocomposites, 7-10 superlattices, [11][12][13] and bulk materials. [14][15][16][17][18] Although high ZT values were achieved in superlattice structures, bulks with improved ZT are ideal for large-scale energy-conversion applications due to their high efficiency of heat transfer and low cost. Enhancing ZT in Bi 2 Te 3 bulk materials by several possible methods has been reported, such as the use of a nanocomposite approach 7,19 and melt spinning.…”

mentioning

confidence: 99%

Electrical and thermoelectric properties of single-wall carbon nanotube doped Bi2Te3

Zhang

Wang

Yeoh

et al. 2012

Applied Physics Letters

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The effects of single-wall carbon nanotube (SWCNT) doping in n-type Bi2Te3 bulk samples on the electrical and thermal transport properties have been studied. Bi2Te3 samples doped with 0–5 wt. % SWCNTs were fabricated using solid state reaction and investigated using x-ray diffraction, transmission electron microscopy, and magneto transport measurements. Results show that the 0.5% doping results in the significant enhancement of the Seebeck coefficience to as high as −231.8 μV/K, giant magneto resistance of up to 110%, reduction of thermal conductivity, and change of sign of the Seebeck coefficient from n to p type depending on the doping level and temperature. The figure of merit, ZT, of the optimum SWCNT doped Bi2Te3 was increased by 25%–40% over a wide temperature range compared to the undoped sample.

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Power Factor Enhancement by Modulation Doping in Bulk Nanocomposites

Cited by 481 publications

References 35 publications

Use of Field-Effect Density Modulation to Increase ZT for Si Nanowires: A Simulation Study

Use of Field-Effect Density Modulation to Increase ZT for Si Nanowires: A Simulation Study

Enhancement of thermoelectric figure-of-merit by resonant states of aluminium doping in lead selenide

Electrical and thermoelectric properties of single-wall carbon nanotube doped Bi2Te3

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