Theoretical Modeling of Thermoelectricity in Bi Nanowires

1998 ◽  
Vol 545 ◽  
Author(s):  
X. Sun ◽  
Z. Zhang ◽  
G. Dresselhaus ◽  
M. S. Dresselhaus ◽  
J. Y. Ying ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Theoretical Model ◽  
Quantum Confinement ◽  
Figure Of Merit ◽  
Wire Diameter ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Crystalline Orientation ◽  
One Dimensional ◽  
Bismuth Nanowires

AbstractBismuth as a semimetal is not a good thermoelectric material in bulk form because of the approximate cancellation between the electron and hole contributions. However, quantum confinement can be introduced by making Bi nanowires to move the lowest conduction subband edge up and the highest valence subband edge down to get a one-dimensional (1D) semiconductor at some critical wire diameter dc. A theoretical model based on the basic band structure of bulk Bi is developed to predict the dependence of these quantities on wire diameter and on the crystalline orientation of the bismuth nanowires. Numerical modeling is performed for trigonal, binary and bisectrix crystal orientations. By carefully tailoring the Bi wire diameter and carrier concentration, substantial enhancement in the thermoelectric figure of merit is expected for small nanowire diameters.

Effect of Quantum-Well Structures on the Thermoelectric Figure of Merit in the Si/Si1-xGex System

1996 ◽  
Vol 452 ◽  
Author(s):  
X. Sun ◽  
M. S. Dresselhaus ◽  
K. L. Wang ◽  
M. O. Tanner
Keyword(s):  
Quantum Well ◽  
Quantum Confinement ◽  
Figure Of Merit ◽  
Molecular Beam ◽  
Theoretical Calculations ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Quantum Well Structures ◽  
Quantum Confinement Effects ◽  
Proof Of Principle

AbstractThe Si/Si1-xGex quantum well system is attractive for high temperature thermoelectric applications and for demonstration of proof-of-principle for enhanced thermoelectric figure of merit Z, since the interfaces and carrier densities can be well controlled in this system. We report theoretical calculations for Z in this system, based on which Si/Si1-xGex quantum-well structures were grown by molecular-beam epitaxy. Thermoelectric and other transport measurements were made, indicating that an increase in Z over bulk values is possible through quantum confinement effects in the Si/Si1-xGex quantum-well structures.

Quantum Confinement Effects on the Thermoelectric Figure of Merit in Si/Si1−xGex System

1997 ◽  
Vol 478 ◽  
Author(s):  
X. Sun ◽  
M. S. Dresselhaus ◽  
K. L. Wang ◽  
M. O. Tanner
Keyword(s):  
Quantum Well ◽  
Quantum Confinement ◽  
Figure Of Merit ◽  
Thin Layers ◽  
Thermoelectric Figure Of Merit ◽  
Barrier Width ◽  
Confinement Effects ◽  
Thermoelectric Figure ◽  
Barrier Layers ◽  
Quantum Confinement Effects

AbstractThe Si/Sil−xGex quantum well system is attractive for high temperature thermoelectric applications and for demonstration of proof-of-principle for enhanced thermoelectric figure of merit Z, since the interfaces and carrier densities can be well controlled in this system. We report here theoretical calculations for Z in this system, and results from theoretical modeling of quantum confinement effects in the presence of δ-doping within the barrier layers. The δ-doping layers are introduced by growing very thin layers of wide band gap materials within the barrier layers in order to increase the effective barrier height within the barriers and thereby reduce the barrier width necessary for the quantum confinement of carriers within the quantum well. The overall figure of merit is thereby enhanced due to the reduced barrier width and hence reduced thermal conductivity, K. The δ-doping should further reduce K in the barriers by introducing phonon scattering centers within the barrier region. The temperature dependence of Z for Si quantum wells is also discussed.

Prospects for Bismuth Nanowires as Thermoelectrics

1998 ◽  
Vol 545 ◽  
Author(s):  
M. S. Dresselhausa ◽  
Z. Zhang ◽  
X. Sun ◽  
J. Y. Ying ◽  
J. Heremans ◽  
...  
Keyword(s):  
Quantum Confinement ◽  
Electronic Band Structure ◽  
Electron Gas ◽  
Electronic Band ◽  
Nanowire Diameter ◽  
Crystalline Orientation ◽  
One Dimensional ◽  
Quantum Confinement Effects ◽  
High Anisotropy ◽  
Bismuth Nanowires

AbstractThe small effective mass of Bi, high anisotropy of its Fermi surface, and the high aspect ratio (length/diameter) of Bi nanowires make this an excellent system for studying quantum confinement effects of a one-dimensional (ID) electron gas in relation to electrical conductivity, thermoelectric power, and thermal conductivity. A theoretical model based on the basic electronic band structure of bulk Bi is suitably modified to describe 1D bismuth nanowires and is used to predict the dependence of these transport properties on nanowire diameter, temperature and crystalline orientation of the bismuth nanowires. Experiments have been carried out on ultra-fine single crystal Bi nanowires (10–120 nm diameter) with a packing density as high as 7 × 1010 wires/cm2 to test the quantum confinement assumptions of the model and the occurrence of a quantum confinement-induced semimetal-to-semiconductor transition as the wire diameter becomes less than 100 nm. Prospects for the use of bismuth nanowires for thermoelectric applications are discussed.

scholarly journals Spin thermoelectric effects of new-style one-dimensional carbon-based nanomaterials

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Yushen Liu ◽  
Jinfu Feng ◽  
Xuefeng Wang
Keyword(s):  
Figure Of Merit ◽  
Graphene Nanoribbons ◽  
Thermal Conductance ◽  
Transmission Function ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Effects ◽  
Thermoelectric Figure ◽  
One Dimensional ◽  
Carbon Chains ◽  
Carbon Based Nanomaterials

Based on first-principles methods, the authors of this paper investigate spin thermoelectric effects of one-dimensional spin-based devices consisting of zigzag-edged graphene nanoribbons (ZGNRs), carbon chains and graphene nanoflake. It is found that the spin-down transmission function is suppressed to zero, while the spin-up transmission function is about 0.25. Therefore, an ideal half-metallic property is achieved. In addition, the phonon thermal conductance is obviously smaller than the electronic thermal conductance. Meantime, the spin Seebeck effects are obviously enhanced at the low-temperature regime (about 80K), resulting in the fact that spin thermoelectric figure of merit can reach about 40. Moreover, the spin thermoelectric figure of merit is always larger than the corresponding charge thermoelectric figure of merit. Therefore, the study shows that they can be used to prepare the ideal thermospin devices.

Extraordinary thermoelectric performance of NaBaBi with degenerate and highly non-parabolic bands compared to LiBaSb and Bi2Te3

2021 ◽  
Author(s):  
Enamul Haque
Keyword(s):  
Fermi Level ◽  
Figure Of Merit ◽  
Thermoelectric Performance ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure

This article reports the extraordinary thermoelectric figure of merit (ZT) of NaBaBi: degenerate bands, instead of the valley degeneracy of Bi2Te3, highly non-parabolic bands, and low DOS near the Fermi level of NaBaBi lead to an extraordinary ZTisotropic ≈ 1.60 at 350 K.

Influence of multi-sintering on the thermoelectric properties of Bi2Sr2Co2Oy ceramics

2019 ◽  
Vol 34 (02) ◽  
pp. 2050019 ◽  
Author(s):  
Y. Zhang ◽  
M. M. Fan ◽  
C. C. Ruan ◽  
Y. W. Zhang ◽  
X.-J. Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Phonon Scattering ◽  
Sintered Sample ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
The Third ◽  
Ceramic Samples ◽  
Optimum Formula

[Formula: see text] ceramic samples have a structure similar to phonon glass electronic crystals, and their thermoelectric properties can be effectively adjusted through repeated grinding and sintering. The results show that multi-sintering can make their grain refined and increase their grain boundary, which will effectively increase density and phonon scattering. Finally, multi-sintering can reduce the resistivity and thermal conductivity, thus obviously improve thermoelectric figure of merit [Formula: see text] of [Formula: see text]. The optimum [Formula: see text] value of 0.26 is achieved at 923 K by the third sintered sample.

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