A Monte Carlo Study on the Effect of Energy Barriers on the Thermoelectric Properties of Si

2016 ◽  
Vol 3 (4) ◽  
Author(s):  
Xanthippi Zianni ◽  
Patrice Chantrenne ◽  
Dario Narducci
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Energy Barrier ◽  
Monte Carlo Study ◽  
Second Phase ◽  
Boltzmann Transport ◽  
Energy Barriers ◽  
Thermoelectric Power Factor ◽  
High Doping Level ◽  
Energy Filtering

AbstractEnergy filtering by energy barriers has been proposed to interpret observations on large thermoelectric power factor (TPF) enhancement in highly doped nanocrystalline Si (nc-Si). Previous Boltzmann transport equation (BTE) modeling indicated that high TPFs could be explained as the result of the presence of energy barriers at the grain boundaries, the high Fermi energy due to the high doping level, and the formation of a low thermal conductivity second phase. To test the assumptions of the BTE modeling and provide more realistic simulations, we have performed Monte Carlo (MC) simulations on the transport properties of composite nc-Si structures. Here, we report on (i) the effect of an energy barrier, and (ii) the effect of multiple barriers on the conductivity and the Seebeck coefficient. In short structures, a TPF enhancement was found and it has been attributed to energy filtering by the energy barrier. The MC indicated that the TE performance can be improved by multiple barriers in close separation. It has been shown that TPF enhancement is possible even when the condition for thermal conductivity non-uniformity across the composite structure is not-fulfilled.

Monte Carlo study on abnormal growth of Goss grains in Fe-3%Si steel induced by second-phase particles

2016 ◽  
Vol 23 (12) ◽  
pp. 1397-1403 ◽  
Author(s):  
Dong-qun Xin ◽  
Cheng-xu He ◽  
Xue-hai Gong ◽  
Hao Wang ◽  
Li Meng ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Second Phase ◽  
Abnormal Growth ◽  
Second Phase Particles

Monte Carlo Modeling of Phonon Transport Using Scattering Phase Functions

2008 ◽  
Author(s):  
Neil Zuckerman ◽  
Jennifer R. Lukes
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Numerical Methods ◽  
Ballistic Transport ◽  
Simulation Method ◽  
Phonon Transport ◽  
Nanometer Scale ◽  
Boltzmann Transport ◽  
Length Scales ◽  
Scale Structures

The calculation of heat transport in nonmetallic materials at small length scales is important in the design of thermoelectric and electronic materials. New designs with quantum dot superlattices (QDS) and other nanometer-scale structures can change the thermal conductivity in ways that are difficult to model and predict. The Boltzmann Transport Equation can describe the propagation of energy via mechanical vibrations in an analytical fashion but remains difficult to solve for the problems of interest. Numerical methods for simulation of propagation and scattering of high frequency vibrational quanta (phonons) in nanometer-scale structures have been developed but are either impractical at micron length scales, or cannot truly capture the details of interactions with nanometer-scale inclusions. Monte Carlo (MC) models of phonon transport have been developed and demonstrated based on similar numerical methods used for description of electron transport [1-4]. This simulation method allows computation of thermal conductivity in materials with length scales LX in the range of 10 nm to 10 μm. At low temperatures the model approaches a ballistic transport simulation and may function for even larger length scales.

Silicon de novo: energy filtering and enhanced thermoelectric performances of nanocrystalline silicon and silicon alloys

2015 ◽  
Vol 3 (47) ◽  
pp. 12176-12185 ◽  
Author(s):  
Dario Narducci ◽  
Stefano Frabboni ◽  
Xanthippi Zianni
Keyword(s):  
Thermoelectric Power ◽  
Power Factor ◽  
De Novo ◽  
Nanocrystalline Silicon ◽  
Second Phase ◽  
Phase Precipitation ◽  
Silicon Alloys ◽  
Thermoelectric Power Factor ◽  
Energy Filtering

Energy filtering due to second-phase precipitation in nanocrystalline silicon may lead to remarkable improvements of its thermoelectric power factor.

Monte Carlo Simulation of the Thermal Conductivity and Phonon Transport in Nanocomposites

2005 ◽  
Author(s):  
Ming-Shan Jeng ◽  
Ronggui Yang ◽  
David Song ◽  
Gang Chen
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Silicon Germanium ◽  
High Efficiency ◽  
Three Dimensional ◽  
Simulation Method ◽  
Phonon Transport ◽  
Boltzmann Transport ◽  
Nanoparticle Composites

This paper presents a Monte Carlo simulation scheme to study the phonon transport and thermal conductivity of nanocomposites. Special attention has been paid to the implementation of periodic boundary condition in Monte Carlo simulation. The scheme is applied to study the thermal conductivity of silicon germanium (Si-Ge) nanocomposites, which are of great interest for high efficiency thermoelectric material development. The Monte Carlo simulation was first validated by successfully reproducing the results of (two dimensional) nanowire composites using the deterministic solution of the phonon Boltzmann transport equation and the experimental thermal conductivity of bulk germanium, and then the validated simulation method was used to study (three dimensional) nanoparticle composites, where Si nanoparticles are embedded in Ge host. The size effects of phonon transport in nanoparticle composites were studied and the results show that the thermal conductivity of nanoparticle composites can be lower than alloy value. It was found that randomly distributed nanopaticles in nanocomposites rendered the thermal conductivity values close to that of periodic aligned patterns.

Monte Carlo Study of Phonon Heat Conduction in Silicon Thin Films: Role of Optical Phonons

2009 ◽  
Author(s):  
Arpit Mittal ◽  
Sandip Mazumder
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Monte Carlo ◽  
Heat Conduction ◽  
Optical Phonons ◽  
Boltzmann Transport ◽  
Phonon Modes ◽  
Silicon Thin Film ◽  
Silicon Thin Films

The Monte Carlo (MC) method has found prolific use in the solution of the Boltzmann Transport Equation (BTE) for phonons for the prediction of non-equilibrium heat conduction in crystalline thin films. This paper contributes to the state-of-the-art by performing a systematic study of the role of the various phonon modes on thermal conductivity predictions—in particular, optical phonons. A procedure to calculate scattering time-scales with the inclusion of optical phonons is described and implemented. The roles of various phonon modes are assessed. It is found that Transverse acoustic (TA) phonons are the primary carriers of energy at low temperatures. At high temperatures (T > 200K), longitudinal acoustic (LA) phonons carry more energy than TA phonons. When optical phonons are included, there is a significant change in the amount of energy carried by various phonons modes. At room temperature, optical modes are found to carry about 25% of the energy at steady state in Silicon thin films. Most importantly, inclusion of optical phonons results in better match with experimental observations for Silicon thin-film thermal conductivity.

Monte Carlo Study of Phonon Transport in Solid Thin Films Including Dispersion and Polarization

2001 ◽  
Vol 123 (4) ◽  
pp. 749-759 ◽  
Author(s):  
Sandip Mazumder ◽  
Arunava Majumdar
Keyword(s):  
Thin Films ◽  
Monte Carlo ◽  
Monte Carlo Study ◽  
Past Research ◽  
Phonon Transport ◽  
Solution Technique ◽  
Boltzmann Transport ◽  
Linear Dispersion ◽  
Silicon Thin Films ◽  
Solid Thin Films

The Boltzmann Transport Equation (BTE) for phonons best describes the heat flow in solid nonmetallic thin films. The BTE, in its most general form, however, is difficult to solve analytically or even numerically using deterministic approaches. Past research has enabled its solution by neglecting important effects such as dispersion and interactions between the longitudinal and transverse polarizations of phonon propagation. In this article, a comprehensive Monte Carlo solution technique of the BTE is presented. The method accounts for dual polarizations of phonon propagation, and non-linear dispersion relationships. Scattering by various mechanisms is treated individually. Transition between the two polarization branches, and creation and destruction of phonons due to scattering is taken into account. The code has been verified and evaluated by close examination of its ability or failure to capture various regimes of phonon transport ranging from diffusive to the ballistic limit. Validation results show close agreement with experimental data for silicon thin films with and without doping. Simulation results show that above 100 K, transverse acoustic phonons are the primary carriers of energy in silicon.

scholarly journals Study of Phonon Transport Across Si/Ge Interfaces Using Full-Band Phonon Monte Carlo Simulation

2021 ◽  
Author(s):  
Ngoc Duc Le ◽  
Brice Davier ◽  
Philippe Dollfus ◽  
Jerome Saint Martin
Keyword(s):  
Thermal Conductivity ◽  
Heat Flux ◽  
Monte Carlo ◽  
Boltzmann Transport Equation ◽  
Phonon Transport ◽  
Nanometer Scale ◽  
Boltzmann Transport ◽  
Ballistic Regime ◽  
Full Band ◽  
Micrometer Scale

Abstract A Full Band Monte Carlo simulatorhas been developed to considerphonon transmission across interfaces disposedperpendicularlyto the heat flux. This solver of the Boltzmann transport equation does not require any assumption on the shape the phonon distribution and can naturally consider all phonon transport regimes from the diffusive to the fully ballistic regime. This simulatoris used to study single and double Si/Ge heterostructures from the micrometer scale downto the nanometer scale,i.e. in all phonon transport regime from fully diffusive toballistic.A methodology to determine the thermal conductivity atthermal interfaces is presented.

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