Monte Carlo Simulations on the Thermoelectric Transport Properties of Width-Modulated Nanowires

Zianni, Xanthippi

doi:10.1007/s11664-015-4217-3

Cited by 10 publications

(11 citation statements)

References 25 publications

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“…Particularly, phonon U scattering relaxation rates and boundary scattering relaxation time are calculated separately in this work, providing qualitative theoretical supports to future MC studies. It is observed the special shape of the bamboo-like boundary plays an essential role in reducing the thermal conductivities as previous reports [25][26][27][28]. Particularly at low temperatures, the thermal conductivities are suppressed distinctly.…”

Section: Resultssupporting

confidence: 77%

“…Termentzidis et al predicated the thermal conductivities of 3C-SiC and 2H-SiC NWs with constant and variable crosssections via the NEMD method [24], in which the physical model was similar to that of bamboo-like NWs. Zianni appraised the impact of diameter modulation on the thermal conductivity reduction in core-shell silicon nanowires [25]. By a kinetic theory model, Zianni et al [26][27][28] investigated transport properties of phonon and electron in diametermodulated nanowires and pointed out the amount of disorder which suppresses thermal conductance deeply according to phonon transmission coefficients.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Wang

2017

Journal of Nanomaterials

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Bamboo-like SiC nanowires (NWs) have specific geometric shapes, which have the potential to suppress thermal conductivity by phonon boundary scattering. In this work, phonon transport behaviors in the 3C-SiC, 4H-SiC, and 6H-SiC crystal lattices are studied by the Monte Carlo (MC) method, including impurity scattering, boundary scattering, and Umklapp scattering. Phonon relaxation times for Umklapp (U) scattering for the above three SiC polytypes are calculated from the respective phonon spectra, which have not been reported in the literature. Diffuse boundary scattering and thermal rectification with different aspect ratios are also studied at different temperatures. It is found that the thermal conductivities of the bamboo-like SiC polytypes can be lowered by two orders of magnitude compared with the bulk values by contributions from boundary scattering. Compared with bamboo-like 4H-SiC and 6H-SiC NWs, 3C-SiC has the largest U scattering relaxation rate and boundary scattering rate, which leads to its lowest thermal conductivities. The thermal conductivity in the positive direction is larger than that in the negative direction because of its lower boundary scattering relaxation rate.

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Section: Resultssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Wang

2017

Journal of Nanomaterials

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“…Semi-classical Monte Carlo simulations are also starting to emerge in TE materials [242,243,244,245,246,247,248,249]. The advantage of MC is that the computational cost increases linearly with the system size and scattering events can be incorporated relatively easily.…”

Section: Simulation Tools For Electronic Transport In Nanostructuresmentioning

confidence: 99%

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

et al. 2020

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The field of thermoelectric materials has undergone a revolutionary transformation over the last couple of decades as a result of the ability to nanostructure and synthesize myriads of materials and their alloys. The ZT figure of merit, which quantifies the performance of a thermoelectric material has more than doubled after decades of inactivity, reaching values larger than two, consistently across materials and temperatures. Central to this ZT improvement is the drastic reduction in the material thermal conductivity due to the scattering of phonons on the numerous interfaces, boundaries, dislocations, point defects, phases, etc., which are purposely included. In these new generation of nanostructured materials, phonon scattering centers of different sizes and geometrical configurations (atomic, nano- and macro-scale) are formed, which are able to scatter phonons of mean-free-paths across the spectrum. Beyond thermal conductivity reductions, ideas are beginning to emerge on how to use similar hierarchical nanostructuring to achieve power factor improvements. Ways that relax the adverse interdependence of the electrical conductivity and Seebeck coefficient are targeted, which allows power factor improvements. For this, elegant designs are required, that utilize for instance non-uniformities in the underlying nanostructured geometry, non-uniformities in the dopant distribution, or potential barriers that form at boundaries between materials. A few recent reports, both theoretical and experimental, indicate that extremely high power factor values can be achieved, even for the same geometries that also provide ultra-low thermal conductivities. Despite the experimental complications that can arise in having the required control in nanostructure realization, in this colloquium, we aim to demonstrate, mostly theoretically, that it is a very promising path worth exploring. We review the most promising recent developments for nanostructures that target power factor improvements and present a series of design ‘ingredients’ necessary to reach high power factors. Finally, we emphasize the importance of theory and transport simulations for materialoptimization, and elaborate on the insight one can obtain from computational tools routinely used in the electronic device communities. Graphical abstract

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“…In this regime, they are determined by scattering effects rather than geometrical quantum confinement variation. [36,37,42,43,80] We investigated such effects for phonons with kinetic theory transport models and Monte Carlo simulations and derived analytical formalism on the dependence of κ ph on modulation-profile characteristic dimensions. [36,37,42] This explicitly showed that κ ph decreases due to geometrically enhanced boundary scattering, decreased transmissivity and ballistic/diffusive transport effects.…”

Section: Evolution Of Researchmentioning

confidence: 99%

Thermoelectric Metamaterials: Nano‐Waveguides for Thermoelectric Energy Conversion and Heat Management at the Nanoscale

Zianni

2021

Adv Elect Materials

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are heterostructures, electronic and phononic superlattices that have been extensively studied since their discovery nearly 100 years ago. [2][3][4][5][6][7][8][9] Electrons and phonons in geometry-modulated nanostructures, nano-waveguides (nWVGs), have attracted extended research interest since the 1980s. [10][11][12][13][14] In 2010, we proposed nWVGs for thermoelectric efficiency enhancement by geometrical control of electron and phonon properties. [15][16][17] Thermoelectric (TE) energy conversion could ideally serve the need of our society for low-cost green energy production, reduction of CO 2 emissions and waste-heat recycling. Low efficiencies of traditional thermoelectric materials prohibited for long widespread thermoelectric applications. In the last 20 years, the efforts of the thermoelectric community concentrated to alternative approaches, such as using low-dimensional and nanostructured materials, to enhance the TE efficiency. Much progress has been achieved and research is continuing along these lines. Currently, another dimension has been added by that thermoelectric materials could power the Internet of things (IoT). [18] Already-achieved record efficiencies should be sufficient for this purpose. Nevertheless, traditional thermoelectric materials are not suitable for integration into the microelectronics industrial processes. Novel strategies to enhance the TE efficiency of technologically important materials are of predominant importance and interest. Thermoelectric metamaterials (THEMMs), nWVGs with enhanced TE properties, can contribute to this task. Their operation is based on the same principles as low-dimensional and nanostructured materials.The discovery of low-dimensional materials revolutionized science and technology provide the fascinating ability to engineer the energy bandstructure and properties of matter with superlattices of different materials. [19][20][21] Superlattices made of low-dimensional constituent materials exhibited improved properties and novel functionalities due to quantum confinement. Shrinking dimensions to the nanoscale and forming low-dimensional nanostructures and nanocomposite materials opened-up new horizons in science and led to the era of nanotechnology.Low-dimensional materials have one or more dimensions small enough (typically in the nanometric range) so that carriers The idea of using metamaterials for thermoelectrics was proposed 10 years ago. Enhanced thermoelectric effects and decreased thermal conduction are theoretically demonstrated due to modification of electrons and phonons by quantum interference between propagating and scattered waves at geometrical discontinuities. These structures are now considered promising for breakthrough in thermoelectric energy conversion and heat management at the nanoscale. They could ideally power the Internet of things. This review is devoted to electron and phonon transport properties of thermoelectric metamaterials in the quantum confinement regime. Enhanced thermoelectric effects and decreased thermal conductiv...

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Monte Carlo Simulations on the Thermoelectric Transport Properties of Width-Modulated Nanowires

Cited by 10 publications

References 25 publications

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Thermal Transport and Rectification Properties of Bamboo-Like SiC Polytypes Nanowires

Hierarchically nanostructured thermoelectric materials: challenges and opportunities for improved power factors

Thermoelectric Metamaterials: Nano‐Waveguides for Thermoelectric Energy Conversion and Heat Management at the Nanoscale

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