A reduction of thermal conductivity of non-periodic Si/Ge superlattice nanowire: Molecular dynamics simulation

Zhang, Chun Wei; Zhou, Hai; Zeng, Yong; Liu, Zheng; Bi, Ke Dong

doi:10.1016/j.ijheatmasstransfer.2018.12.041

Cited by 23 publications

(12 citation statements)

References 60 publications

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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%

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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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Section: Resultsmentioning

confidence: 99%

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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“…9) Among such low-dimensional materials, nanowires (NWs) also attract attention, and in particular, Si and Ge NWs, which are characterized by sufficiently high mobility of charge carriers. 10,11) Si and Ge NWs have been studied extensively, [10][11][12][13][14][15][16][17][18][19][20][21] since Si and Ge are common materials in microelectronics. Numerical estimates of κ L of homogeneous Si and Ge nanowires are in the range of ∼10−25 W/(m•K) and ∼6−14 W/(m•K), respectively, 15,16,19) and these values are an order of magnitude less than the one for Si and Ge bulks (∼140 W/(m•K) 22) and ∼55 W/(m•K), 23) respectively).…”

Section: Introductionmentioning

confidence: 99%

Effect of morphology on the phonon thermal conductivity in Si/Ge superlattice nanowires

Khaliava¹,

Khamets²,

Safronov³

et al. 2022

Jpn. J. Appl. Phys.

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We used nonequilibrium molecular dynamics to investigate the role of morphology in the phonon thermal conductivity of 〈100〉, 〈110〉, 〈111〉 and 〈112〉-oriented Si/Ge superlattice nanowires at 300 K. Such nanowires with 〈112〉 growth direction were found to possess the lowest values of the thermal conductivity [1.6 W/(m·K) for a Si and Ge segment thickness of ∼3 nm] due to the lowest average group velocity and highly effective {113} facets and Si/Ge(112) interface for phonon-surface and phonon-interface scattering, respectively. Comparison with homogeneous and core/shell Si and Ge nanowires showed that the superlattice morphology is the most efficient to suppress the thermal conductivity.

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“…In order to further elevate the figure of merit , the authors of a number of theoretical works proposed a wide range of methods aimed at reducing the thermal conductivity of nanowires. In particular, those methods include the optimization of geometric parameters (such as the cross-section [11], the crystallographic orientation [12], and the degree of structure porosity [13]), the variation of the composite [14] and defect [15] content in nanowires, their deformation [16], and the creation of superlattices [17]. On the other hand, modern experimental studies also open up new ways to control the value of the thermal conductivity in nanowires.…”

Section: Introductionmentioning

confidence: 99%

Теплопровідність Si нанониток з аморфною SiO2 обо-лонкою: молекулярно-динамічний розрахунок

et al. 2021

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Методом нерiвноважної молекулярної динамiки дослiджено процеси теплового транспорту в Si нанонитках, покритих оболонкою аморфного SiO2. Розглянуто вплив товщини аморфного шару, радiуса кристалiчного кремнiєвого ядра I температури на величину коефiцiєнта теплопровiдностi нанониток. Встановлено, що збiльшення товщини аморфної оболонки зумовлює зменшення теплопровiдностi Si/SiO2 нанониток типу ядро-оболонка. Результати також показують, що теплопровiднiсть Si/SiO2 нанониток при 300 К зростає зi збiльшенням площi поперечного перерiзу кристалiчного Si ядра. Виявлено, що температурна залежнiсть коефiцiєнта теплопровiдностi Si/SiO2 нанониток типу ядро-оболонка є суттєво слабшою, нiж в кристалiчних кремнiєвих нанонитках. Показано, що така вiдмiннiсть є результатом рiзних домiнуючих механiзмiв фононного розсiювання в нанонитках. Отриманi результати демонструють, що нанонитки Si/SiO2 є перспективним матерiалом для термоелектричних застосувань.

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A reduction of thermal conductivity of non-periodic Si/Ge superlattice nanowire: Molecular dynamics simulation

Cited by 23 publications

References 60 publications

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

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

Effect of morphology on the phonon thermal conductivity in Si/Ge superlattice nanowires

Теплопровідність Si нанониток з аморфною SiO2 обо-лонкою: молекулярно-динамічний розрахунок

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