scholarly journals Carrier concentration effect and other structure-related parameters on lattice thermal conductivity of Si nanowires

2017 ◽  
Vol 40 (3) ◽  
pp. 599-607 ◽  
Author(s):  
Ibrahim N Qader ◽  
M S Omar
Keyword(s):  
Thermal Conductivity ◽  
Carrier Concentration ◽  
Lattice Thermal Conductivity ◽  
Concentration Effect ◽  
Si Nanowires

Theory of Thermal Conductivity of Micro- and Nano-structured Materials

2009 ◽  
Vol 1172 ◽  
Author(s):  
Gyaneshwar P. Srivastava
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Polycrystalline Diamond ◽  
Comprehensive Treatment ◽  
Si Nanowires ◽  
Quantitative Investigation ◽  
Debye Relaxation ◽  
Structured Materials ◽  
20 Nm

AbstractWe provide a brief discussion of the Boltzmann equation derived Callaway-Debye relaxation time theory of lattice thermal conductivity of micro- and nano-structured materials (of size greater than 20 nm. Incorporated in the theory is a comprehensive treatment of three-phonon scattering events. Using numerical results from this theory, we present a quantitative investigation of the magnitude and temperature variation of the conductivity of CVD polycrystalline diamond films, suspended GaAs nanostructures, Si nanowires, and AlN micro- and nano-ceramics.

scholarly journals Electrical Transport and Thermoelectric Properties of SnSe–SnTe Solid Solution

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3854 ◽  
Author(s):  
Jun-Young Cho ◽  
Muhammad Siyar ◽  
Woo Chan Jin ◽  
Euyheon Hwang ◽  
Seung-Hwan Bae ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Electrical Conductivity ◽  
Single Crystal ◽  
Carrier Concentration ◽  
Electrical Transport ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Practical Applications ◽  
Defect Sites

SnSe is considered as a promising thermoelectric (TE) material since the discovery of the record figure of merit (ZT) of 2.6 at 926 K in single crystal SnSe. It is, however, difficult to use single crystal SnSe for practical applications due to the poor mechanical properties and the difficulty and cost of fabricating a single crystal. It is highly desirable to improve the properties of polycrystalline SnSe whose TE properties are still not near to that of single crystal SnSe. In this study, in order to control the TE properties of polycrystalline SnSe, polycrystalline SnSe–SnTe solid solutions were fabricated, and the effect of the solid solution on the electrical transport and TE properties was investigated. The SnSe1−xTex samples were fabricated using mechanical alloying and spark plasma sintering. X-ray diffraction (XRD) analyses revealed that the solubility limit of Te in SnSe1−xTex is somewhere between x = 0.3 and 0.5. With increasing Te content, the electrical conductivity was increased due to the increase of carrier concentration, while the lattice thermal conductivity was suppressed by the increased amount of phonon scattering. The change of carrier concentration and electrical conductivity is explained using the measured band gap energy and the calculated band structure. The change of thermal conductivity is explained using the change of lattice thermal conductivity from the increased amount of phonon scattering at the point defect sites. A ZT of ~0.78 was obtained at 823 K from SnSe0.7Te0.3, which is an ~11% improvement compared to that of SnSe.

scholarly journals Influence of Pd Doping on Electrical and Thermal Properties of n-Type Cu0.008Bi2Te2.7Se0.3 Alloys

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4080 ◽  
Author(s):  
Se Yun Kim ◽  
Hyun-Sik Kim ◽  
Kyu Hyoung Lee ◽  
Hyun-jun Cho ◽  
Sung-sil Choo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Carrier Concentration ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Energy Conversion Efficiency ◽  
Thermoelectric Figure ◽  
Pd Doping ◽  
Effect Of Pd

Doping is known as an effective way to modify both electrical and thermal transport properties of thermoelectric alloys to enhance their energy conversion efficiency. In this project, we report the effect of Pd doping on the electrical and thermal properties of n-type Cu0.008Bi2Te2.7Se0.3 alloys. Pd doping was found to increase the electrical conductivity along with the electron carrier concentration. As a result, the effective mass and power factors also increased upon the Pd doping. While the bipolar thermal conductivity was reduced with the Pd doping due to the increased carrier concentration, the contribution of Pd to point defect phonon scattering on the lattice thermal conductivity was found to be very small. Consequently, Pd doping resulted in an enhanced thermoelectric figure of merit, zT, at a high temperature, due to the enhanced power factor and the reduced bipolar thermal conductivity.

scholarly journals Efficient interlayer charge release for high-performance layered thermoelectrics

2020 ◽  
Author(s):  
Hao Zhu ◽  
Zhou Li ◽  
Chenxi Zhao ◽  
Xingxing Li ◽  
Jinlong Yang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
High Performance ◽  
Lattice Thermal Conductivity ◽  
Transport Barrier ◽  
High Seebeck Coefficient ◽  
Valence Bands ◽  
Increase Carrier Concentration

Abstract Many layered superlattice materials intrinsically possess large Seebeck coefficient and low lattice thermal conductivity, but poor electrical conductivity because of the interlayer transport barrier for charges, which has become a stumbling block for achieving high thermoelectric performance. Herein, taking BiCuSeO superlattice as an example, it is demonstrated that efficient interlayer charge release can increase carrier concentration, thereby activating multiple Fermi pockets through Bi/Cu dual vacancies and Pb codoping. Experimental results reveal that the extrinsic charges, which are introduced by Pb and initially trapped in the charge-reservoir [Bi2O2]2+ sublayers, are effectively released into [Cu2Se2]2− sublayers via the channels bridged by Bi/Cu dual vacancies. This efficient interlayer charge release endows dual-vacancy- and Pb-codoped BiCuSeO with increased carrier concentration and electrical conductivity. Moreover, with increasing carrier concentration, the Fermi level is pushed down, activating multiple converged valence bands, which helps to maintain a relatively high Seebeck coefficient and yield an enhanced power factor. As a result, a high ZT value of ∼1.4 is achieved at 823 K in codoped Bi0.90Pb0.06Cu0.96SeO, which is superior to that of pristine BiCuSeO and solely doped samples. The present findings provide prospective insights into the exploration of high-performance thermoelectric materials and the underlying transport physics.

Extraordinary role of Zn in enhancing thermoelectric performance of Ga-doped n-type PbTe

2022 ◽  
Author(s):  
Zhong-zhen Luo ◽  
Songting Cai ◽  
Shiqiang Hao ◽  
Trevor Bailey ◽  
Yubo Luo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carrier Concentration ◽  
Lattice Thermal Conductivity ◽  
Thermoelectric Performance ◽  
Phonon Coupling ◽  
Electron Phonon Coupling ◽  
Ga Doping ◽  
Role Of Zn

Although Ga doping can weaken the electron phonon coupling of n-type PbTe, Ga-doped PbTe has a relatively low carrier concentration (n) and high lattice thermal conductivity (κlat), resulting in a...

Thermoelectric Properties of Solid-State Synthesized Magnesium Silicides Doped with Group BI-III Elements

2012 ◽  
Vol 724 ◽  
pp. 385-388 ◽  
Author(s):  
Sin Wook You ◽  
Soon Mok Choi ◽  
Won Seon Seo ◽  
Sun Uk Kim ◽  
Kyung Wook Jang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Solid State ◽  
Mechanical Alloying ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Solid State Reaction ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Group B

Group BI(Cu, Ag)-, BII(Zn)- and BIII(Al, In)-doped Mg2Si compounds were synthesized by solid state reaction and mechanical alloying. Electronic transport properties (Hall coefficient, carrier concentration and mobility) and thermoelectric properties (Seebeck coefficient, electrical conductivity, power factor, thermal conductivity and figure of merit) were examined. Mg2Si powder was synthesized successfully by solid state reaction at 773 K for 6 h and doped by mechanical alloying for 24 h. It was fully consolidated by hot pressing at 1073 K for 1 h. The electrical conductivity increased by doping due to an increase in the carrier concentration. However, the thermal conductivity did not changed significantly by doping, which was due to much larger contribution of the lattice thermal conductivity over the electronic thermal conductivity. Group BIII(Al, In) elements were more effective to enhance the thermoelectric properties of Mg2Si.

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