Effect of period length distribution on the thermal conductivity of Si/Ge superlattice

Liu, Yingguang; Hao, Jiang-Shuai; Chernatynskiy, Aleksandr V.; Ren, Guoliang; Zhang, Jingwen

doi:10.1016/j.ijthermalsci.2021.107157

Cited by 4 publications

(5 citation statements)

References 52 publications

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“…When the period length increased from 59.64 Å to 179.4 conductivity gradually decreased and reached the minimum value W/m•K. Then, with the increase in the period length, the thermal condu The thermal conductivity was 139.19 ± 3.66 W/m•K with a period length existence of minimum thermal conductivity as a function of the period perlattices has been observed in experiments and simulations [47,63,64]; characteristic of the coherent-to-incoherent transition. When the period 179.40 Å , the formation of the minibands reduces the phonon group velo…”

Section: Effect Of Period Lengthmentioning

confidence: 70%

“…The thermal conductivity was 139.19 ± 3.66 W/m•K with a period length of 358.73 Å. The existence of minimum thermal conductivity as a function of the period length of the superlattices has been observed in experiments and simulations [47,63,64]; it is an important characteristic of the coherent-to-incoherent transition. When the period length is below 179.40 Å, the formation of the minibands reduces the phonon group velocity.…”

Section: Effect Of Period Lengthmentioning

confidence: 79%

“…The period length of the uniform 3C/4H-SiC nanowires was defined as the total thickness of a pair of continuous 3C and 4H layers (Figure 1e). The period length of the gradient period 3C/4H-SiC nanowires was calculated as the sum of the average length of the 3C and 4H (Figure 1f) [46,47].…”

Section: Crystal Structural and Modeling Detailsmentioning

confidence: 99%

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Thermal Conductivity of 3C/4H-SiC Nanowires by Molecular Dynamics Simulation

Yin,

Shi,

et al. 2023

Nanomaterials

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Silicon carbide (SiC) is a promising material for thermoelectric power generation. The characterization of thermal transport properties is essential to understanding their applications in thermoelectric devices. The existence of stacking faults, which originate from the “wrong” stacking sequences of Si–C bilayers, is a general feature of SiC. However, the effects of stacking faults on the thermal properties of SiC are not well understood. In this study, we evaluated the accuracy of Tersoff, MEAM, and GW potentials in describing the thermal transport of SiC. Additionally, the thermal conductivity of 3C/4H-SiC nanowires was investigated using non-equilibrium molecular dynamics simulations (NEMD). Our results show that thermal conductivity exhibits an increase and then saturation as the total lengths of the 3C/4H-SiC nanowires vary from 23.9 nm to 95.6 nm, showing the size effect of molecular dynamics simulations of the thermal conductivity. There is a minimum thermal conductivity, as a function of uniform period length, of the 3C/4H-SiC nanowires. However, the thermal conductivities of nanowires weakly depend on the gradient period lengths and the ratio of 3C/4H. Additionally, the thermal conductivity of 3C/4H-SiC nanowires decreases continuously from compressive strain to tensile strain. The reduction in thermal conductivity suggests that 3C/4H-SiC nanowires have potential applications in advanced thermoelectric devices. Our study provides insights into the thermal transport properties of SiC nanowires and can guide the development of SiC-based thermoelectric materials.

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Section: Effect Of Period Lengthmentioning

confidence: 70%

Section: Effect Of Period Lengthmentioning

confidence: 79%

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Thermal Conductivity of 3C/4H-SiC Nanowires by Molecular Dynamics Simulation

Yin,

Shi,

et al. 2023

Nanomaterials

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“…A broadened distribution of QGs’ spacings can further lower κ lattice . 55 , 56 This can be achieved by the addition of the Re element (see supplementary discussion for details). For example, in Ge 0.867 Re 0.003 Bi 0.087 Te, the modulated distribution of QGs results in the lowered κ lattice (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Besides, the more diffusely distributed QGs (Fig. 5a ) can scatter phonons with a larger range of mean free paths (MFP) to further lower lattice thermal conductivity 55 , 56 , while not so diffusely distributed QGs can only scatter a part of these phonons. This mechanism is similar to applying all-scale defects to lower lattice thermal conductivity 57 .…”

Section: Resultsmentioning

confidence: 99%

Tunable quantum gaps to decouple carrier and phonon transport leading to high-performance thermoelectrics

Wang

et al. 2022

Nat Commun

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Thermoelectrics enable direct heat-to-electricity transformation, but their performance has so far been restricted by the closely coupled carrier and phonon transport. Here, we demonstrate that the quantum gaps, a class of planar defects characterized by nano-sized potential wells, can decouple carrier and phonon transport by selectively scattering phonons while allowing carriers to pass effectively. We choose the van der Waals gap in GeTe-based materials as a representative example of the quantum gap to illustrate the decoupling mechanism. The nano-sized potential well of the quantum gap in GeTe-based materials is directly visualized by in situ electron holography. Moreover, a more diffused distribution of quantum gaps results in further reduction of lattice thermal conductivity, which leads to a peak ZT of 2.6 at 673 K and an average ZT of 1.6 (323–723 K) in a GeTe system. The quantum gap can also be engineered into other thermoelectrics, which provides a general method for boosting their thermoelectric performance.

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