Thin Film In-Plane Silicon Thermal Conductivity Dependence on Molecular Dynamics Surface Boundary Conditions

The in-plane thermal conductivity of thin silicon films is predicted using equilibrium molecular dynamics, the Stillinger-Weber potential and the Green-Kubo relationship. Film thicknesses range from 2 to 200 nm. Periodic boundary conditions are used in the directions parallel to the thin film surfaces. Two different strategies are evaluated to treat the atoms on the surfaces perpendicular to the thin film direction: adding four layers of atoms kept frozen at their crystallographic positions, or restraining the atoms near the surfaces with a repulsive potential. We show that when the thin-film thickness is smaller than the phonon mean free path, the predictions of the in-plane thermal conductivity at 1000K differ significantly depending on the potential applied to the atoms near the surfaces. In this limit, the experimentally observed trend of decreasing thermal conductivity with decreasing film thickness is predicted when the surface atoms are subject to a repulsive potential in addition to the Stillinger-Weber potential, but not when they are limited by frozen atoms.

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Molecular Dynamics Simulation on the Out-of Plane Thermal Conductivity of Single-Crystal Carbon Thin Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.60-61.430 ◽

2009 ◽

Vol 60-61 ◽

pp. 430-434 ◽

Cited By ~ 1

Author(s):

Xing Li Zhang ◽

Zhao Wei Sun ◽

Guo Qiang Wu

Keyword(s):

Thin Film ◽

Thin Films ◽

Thermal Conductivity ◽

Molecular Dynamics ◽

Potential Energy ◽

Film Thickness ◽

Single Crystal ◽

Diamond Crystal ◽

Dynamics Simulation ◽

Crystal Direction

In this article, we select corresponding Tersoff potential energy to build potential energy model and investigate the thermal conductivities of single-crystal carbon thin-film. The equilibrium molecular dynamics (EMD) method is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (001), and the non-equilibrium molecular dynamics (NEMD) is used to calculate the nanometer thin film thermal conductivity of diamond crystal at crystal direction (111). The results of calculations demonstrate that the nanometer thin film thermal conductivity of diamond crystal is remarkably lower than the corresponding bulk experimental data and increase with increasing the film thickness, and the nanometer thin film thermal conductivity of diamond crystal relates to film thickness linearly in the simulative range. The nanometer thin film thermal conductivity also demonstrates certain regularity with the change of temperature. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of nanometer thin films.

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Molecular Dynamics Simulation of Thermal Conductivity of Silicon Films Using Environment-Dependent Interatomic Potential

Volume 4 ◽

10.1115/ht-fed2004-56725 ◽

2004 ◽

Cited By ~ 1

Author(s):

Xinwei Wang ◽

Cecil Lawrence

Keyword(s):

Thermal Conductivity ◽

Molecular Dynamics ◽

Film Thickness ◽

Lattice Boltzmann ◽

Interatomic Potential ◽

Silicon Films ◽

Dynamics Simulation ◽

Nonequilibrium Molecular Dynamics ◽

Boltzmann Method ◽

Weber Potential

In this work, nonequilibrium molecular dynamics is used to predict the thermal conductivity of nanoscale thin silicon films in the thickness direction. Recently developed environment-dependent interatomic potential for silicon, which offers considerable improvement over the more common Stillinger-Weber potential, is used. Silicon films of various thicknesses are modeled to establish the variation of thermal conductivity with the film thickness. The obtained relationship between the thermal conductivity and the film thickness is compared with the results of the Lattice Boltzmann method, and sound agreement is observed.

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In-Plane and Out-Of-Plane Thermal Conductivity of Silicon Thin Films Predicted by Molecular Dynamics

Journal of Heat Transfer ◽

10.1115/1.2352781 ◽

2006 ◽

Vol 128 (11) ◽

pp. 1114-1121 ◽

Cited By ~ 58

Author(s):

Carlos J. Gomes ◽

Marcela Madrid ◽

Javier V. Goicochea ◽

Cristina H. Amon

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Molecular Dynamics ◽

Film Thickness ◽

Interatomic Potential ◽

Mean Free Path ◽

Free Boundaries ◽

Silicon Thin Films ◽

Out Of Plane ◽

Bulk Phonon

The thermal conductivity of silicon thin films is predicted in the directions parallel and perpendicular to the film surfaces (in-plane and out-of-plane, respectively) using equilibrium molecular dynamics, the Green-Kubo relation, and the Stillinger-Weber interatomic potential. Three different boundary conditions are considered along the film surfaces: frozen atoms, surface potential, and free boundaries. Film thicknesses range from 2to217nm and temperatures from 300to1000K. The relation between the bulk phonon mean free path (Λ) and the film thickness (ds) spans from the ballistic regime (Λ⪢ds) at 300K to the diffusive, bulk-like regime (Λ⪡ds) at 1000K. When the film is thin enough, the in-plane and out-of-plane thermal conductivity differ from each other and decrease with decreasing film thickness, as a consequence of the scattering of phonons with the film boundaries. The in-plane thermal conductivity follows the trend observed experimentally at 300K. In the ballistic limit, in accordance with the kinetic and phonon radiative transfer theories, the predicted out-of-plane thermal conductivity varies linearly with the film thickness, and is temperature-independent for temperatures near or above the Debye’s temperature.

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Silicon Thin Film Thermal Conductivity in Ballistic and Diffusive Regimes Predicted by Molecular Dynamics

Heat Transfer: Volume 4 ◽

10.1115/ht2005-72434 ◽

2005 ◽

Author(s):

Carlos J. Gomes ◽

Marcela Madrid ◽

Javier V. Goicochea ◽

Cristina H. Amon

Keyword(s):

Thin Films ◽

Thermal Conductivity ◽

Molecular Dynamics ◽

Film Thickness ◽

Interatomic Potential ◽

Mean Free Path ◽

Technical Conference ◽

Silicon Thin Film ◽

Silicon Thin Films ◽

Out Of Plane

The thermal conductivity of silicon thin films is predicted in the directions parallel and perpendicular to the film surfaces (in-plane and out-of-plane, respectively) using equilibrium molecular dynamics, the Green-Kubo relationship and the Stillinger-Weber interatomic potential. Film thicknesses range from 2 to 220 nm and temperatures from 300 to 1000 K. In this range of temperatures, the relation between the phonon mean free path (Λ) and the film thickness (ds) spans from the ballistic regime (≫ ds) to the diffusive, bulk-like regime (≪ ds). We show that equilibrium molecular dynamics and the Green-Kubo relationship can be applied to the study of the thermal conductivity of thin films in the ballistic, transitional and diffusive regimes. When the film is thin enough, the thermal conductivity becomes orthotropic and decreases with decreasing film thickness as a consequence of the scattering of phonons with the film boundaries. The in-plane thermal conductivity follows the trend observed experimentally at 300 K. In the ballistic limit, in accordance with the kinetic theory, the predicted out-of-plane thermal conductivity varies linearly with the film thickness and is temperature-independent for temperatures near or above Debye’s temperature. This paper was also originally published as part of the Proceedings of the ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems.

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Out-of-Plane Thermal Conductivity of Silicon Thin Film Doped with Germanium

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1082.459 ◽

2014 ◽

Vol 1082 ◽

pp. 459-462

Author(s):

Hui Chen ◽

Wei Yu Chen ◽

Yun Fei Chen ◽

Ke Dong Bi

Keyword(s):

Thin Film ◽

Thermal Conductivity ◽

Film Thickness ◽

Dynamics Simulation ◽

Silicon Thin Film ◽

Doping Density ◽

Average Temperature ◽

Out Of Plane ◽

Non Equilibrium Molecular Dynamics ◽

Weber Potential

The out-of-plane thermal conductivity of silicon thin film doped with germanium is calculated by non-equilibrium molecular dynamics simulation using the Stillinger-Weber potential model. The silicon thin film is doped with germanium atoms in a random doping pattern with a doping density of 5% and 50% respectively. The effect of silicon thin film thickness on its thermal conductivity is investigated. The simulated thicknesses of silicon thin film doped with germanium range from 2.2 to 10.9 nm at an average temperature 300K. The simulation results indicate that the out-of-plane thermal conductivity of the silicon thin film doped with germanium decreases linearly with the decreasing film thickness. As for the film thickness of 9.8nm and the average temperature ranging from 250 to 1000 K, the investigation shows that the temperature dependence of the film thermal conductivity is not sensitive.

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Surface boundary conditions for the numerical solution of the Euler equations

10.2514/6.1993-3334 ◽

1993 ◽

Cited By ~ 3

Author(s):

A. DADONE ◽

B. GROSSMAN

Keyword(s):

Boundary Conditions ◽

Numerical Solution ◽

Euler Equations ◽

Surface Boundary ◽

Surface Boundary Conditions

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Establishing time-varying tidal and non-tidal water surface boundary conditions can improve typical year estimations for green infrastructure based Long-Term Control Plan wet-weather models

Proceedings of the Water Environment Federation ◽

10.2175/193864718825138709 ◽

2018 ◽

Vol 2018 (7) ◽

pp. 5638-5654

Author(s):

Eileen Althouse ◽

Julie Midgette ◽

Hao Zhang ◽

Gary Martens

Keyword(s):

Boundary Conditions ◽

Green Infrastructure ◽

Water Surface ◽

Surface Boundary ◽

Time Varying ◽

Control Plan ◽

Tidal Water ◽

Surface Boundary Conditions ◽

Wet Weather

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Ballistic Heat Transport in Nanocomposite: The Role of the Shape and Interconnection of Nanoinclusions

Nanomaterials ◽

10.3390/nano11081982 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1982

Author(s):

Paul Desmarchelier ◽

Alice Carré ◽

Konstantinos Termentzidis ◽

Anne Tanguy

Keyword(s):

Thermal Conductivity ◽

Molecular Dynamics ◽

Molecular Dynamics Simulations ◽

Free Path ◽

Mean Free Path ◽

Strong Increase ◽

Moderate Increase ◽

Energy Propagation ◽

The Mean ◽

Dynamics Simulations

In this article, the effect on the vibrational and thermal properties of gradually interconnected nanoinclusions embedded in an amorphous silicon matrix is studied using molecular dynamics simulations. The nanoinclusion arrangement ranges from an aligned sphere array to an interconnected mesh of nanowires. Wave-packet simulations scanning different polarizations and frequencies reveal that the interconnection of the nanoinclusions at constant volume fraction induces a strong increase of the mean free path of high frequency phonons, but does not affect the energy diffusivity. The mean free path and energy diffusivity are then used to estimate the thermal conductivity, showing an enhancement of the effective thermal conductivity due to the existence of crystalline structural interconnections. This enhancement is dominated by the ballistic transport of phonons. Equilibrium molecular dynamics simulations confirm the tendency, although less markedly. This leads to the observation that coherent energy propagation with a moderate increase of the thermal conductivity is possible. These findings could be useful for energy harvesting applications, thermal management or for mechanical information processing.

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