Monte Carlo Study on Thermal Transport in Si/Ge Superlattice Basing on Phonon Dispersion Discrepancies

2011 ◽  
Vol 284-286 ◽  
pp. 392-395
Author(s):  
Zan Wang ◽  
Hong Yu Zhu ◽  
Yi Wu Ruan
Keyword(s):  
Monte Carlo ◽  
Thermal Transport ◽  
Phonon Dispersion ◽  
Monte Carlo Model ◽  
Monte Carlo Study ◽  
The Other ◽  
Pass Through

Based on the classical diffuse mismatch model (DMM), the dedicated Monte Carlo model for Si/Ge superlattice is proposed and the method to cope with the scattering at the interface is provided. In this model, phonons transport between two different materials can be taken as the movements between the different phonon dispersion relationships. If there is a corresponding position in the other material, the phonon with a given frequency will be able to pass through the interface, otherwise it will be reflected.

scholarly journals Thermal transport in nanocrystalline Si and SiGe by ab initio based Monte Carlo simulation

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Lina Yang ◽  
Austin J. Minnich
Keyword(s):  
Thermal Conductivity ◽  
Monte Carlo ◽  
Ab Initio ◽  
Grain Boundaries ◽  
Thermal Transport ◽  
Phonon Scattering ◽  
Phonon Dispersion ◽  
Computational Study ◽  
Phonon Transport ◽  
Nanocrystalline Si

Abstract Nanocrystalline thermoelectric materials based on Si have long been of interest because Si is earth-abundant, inexpensive, and non-toxic. However, a poor understanding of phonon grain boundary scattering and its effect on thermal conductivity has impeded efforts to improve the thermoelectric figure of merit. Here, we report an ab-initio based computational study of thermal transport in nanocrystalline Si-based materials using a variance-reduced Monte Carlo method with the full phonon dispersion and intrinsic lifetimes from first-principles as input. By fitting the transmission profile of grain boundaries, we obtain excellent agreement with experimental thermal conductivity of nanocrystalline Si [Wang et al. Nano Letters 11, 2206 (2011)]. Based on these calculations, we examine phonon transport in nanocrystalline SiGe alloys with ab-initio electron-phonon scattering rates. Our calculations show that low energy phonons still transport substantial amounts of heat in these materials, despite scattering by electron-phonon interactions, due to the high transmission of phonons at grain boundaries, and thus improvements in ZT are still possible by disrupting these modes. This work demonstrates the important insights into phonon transport that can be obtained using ab-initio based Monte Carlo simulations in complex nanostructured materials.

A Solution to the Effect of Sample Size on Outlier Elimination

1994 ◽  
Vol 47 (3) ◽  
pp. 631-650 ◽  
Author(s):  
Mark Van Selst ◽  
Pierre Jolicoeur
Keyword(s):  
Monte Carlo ◽  
Standard Deviation ◽  
Sample Size ◽  
Monte Carlo Study ◽  
The Other ◽  
Recursive Procedure ◽  
Elimination Procedure ◽  
New Procedures

Results from a Monte Carlo study demonstrate how a non-recursive, a simple recursive, a modified recursive, and a hybrid outlier elimination procedure are influenced by population skew and sample size. All the procedures are based on computing a mean and a standard deviation from a sample in order to determine whether an observation is an outlier. Miller (1991) showed that the estimated mean produced by the simple non-recursive procedure can be affected by sample size and that this effect can produce a bias in certain kinds of experiments. We extended this result to the other three procedures. We also create two new procedures in which the criterion used to identify outliers is adjusted as a function of sample size so as to produce results that are unaffected by sample size.

Monte Carlo Simulation of Diffusion with Uniform Sinks and Sources for Vacancies

2005 ◽  
Vol 237-240 ◽  
pp. 1168-1173 ◽  
Author(s):  
Jaroslav Ženíšek ◽  
Jiří Svoboda ◽  
Franz Dieter Fischer
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Monte Carlo Model ◽  
Kirkendall Effect ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Self Consistent

A new concept of generation and annihilation of vacancies at uniform sinks and sources for vacancies is incorporated into the standard Monte Carlo model for vacancy mediated diffusion. This model enables to treat the vacancy wind as well as the deformation of the specimen and the shift of the Kirkendall plane. The Monte Carlo model is used for the testing of the recent phenomenological theories of diffusion by Darken, Manning and Moleko. The agreement with the self-consistent Moleko theory is excellent. On the other hand the agreement with the classical Darken theory used very often for the explanation of the Kirkendall effect is rather poor.

scholarly journals Monte Carlo Study of UAV-Measurable Albedo over Arctic Sea Ice

2018 ◽  
Vol 35 (1) ◽  
pp. 57-66 ◽  
Author(s):  
Igor Podgorny ◽  
Dan Lubin ◽  
Donald K. Perovich
Keyword(s):  
Monte Carlo ◽  
Sea Ice ◽  
Energy Budget ◽  
Monte Carlo Model ◽  
Lower Troposphere ◽  
Monte Carlo Study ◽  
Open Water ◽  
Arctic Sea Ice ◽  
Inhomogeneous Surface ◽  
The Impact

AbstractIn anticipation that unmanned aerial vehicles (UAVs) will have a useful role in atmospheric energy budget studies over sea ice, a Monte Carlo model is used to investigate three-dimensional radiative transfer over a highly inhomogeneous surface albedo involving open water, sea ice, and melt ponds. The model simulates the spatial variability in 550-nm downwelling irradiance and albedo that a UAV would measure above this surface and underneath an optically thick, horizontally homogeneous cloud. At flight altitudes higher than 100 m above the surface, an airborne radiometer will sample irradiances that are greatly smoothed horizontally as a result of photon multiple reflection. If one is interested in sampling the local energy budget contrasts between specific surface types, then the UAV must fly at a low altitude, typically within 20 m of the surface. Spatial upwelling irradiance variability in larger open water features, on the order of 1000 m wide, will remain apparent as high as 500 m above the surface. To fully investigate the impact of surface feature variability on the energy budget of the lower troposphere ice–ocean system, a UAV needs to fly at a variety of altitudes to determine how individual features contribute to the area-average albedo.

scholarly journals Monte Carlo study of temperature-dependent non-diffusive thermal transport in Si nanowires

2017 ◽  
Vol 124 ◽  
pp. 17-21 ◽  
Author(s):  
Lei Ma ◽  
Riguo Mei ◽  
Mengmeng Liu ◽  
Xuxin Zhao ◽  
Qixing Wu ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Thermal Transport ◽  
Monte Carlo Study ◽  
Si Nanowires ◽  
Temperature Dependent

Monte Carlo Simulation of the Growth of ZnSe by MBE

1986 ◽  
Vol 77 ◽  
Author(s):  
R. Venkatasubramanian ◽  
N. Otsuka ◽  
S. Datta ◽  
L. A. Kolodziejski ◽  
R. L. Gunshor
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Molecular Beam ◽  
Flux Ratio ◽  
Monte Carlo Study ◽  
The Other ◽  
Structural Quality ◽  
Wide Range

ABSTRACTA Monte Carlo study of the growth of ZnSe by Molecular beam epitaxy is presented. The study is focused on the role of surface kinetic reactions on the structural quality of the epilayers. Two different models for the incorporation of Se molecules, one with a highly reactive physisorbed state and the other with a relatively nonreactive physisorbed state are employed for simulations. It is shown that the structural quality of the epilayers is very sensitive to the flux ratio if the physisorbed state is relatively nonreactive. It is also shown that if the physisorbed state is highly reactive, good quality epilayers are obtained over a wide range of flux ratio.

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