A new lattice thermal conductivity model of a thin-film semiconductor

Huang, Mei‐Jiau; Chang, Tsun-Kuo; Chong, Wen-Yen; Liu, Chun-Kai; Yu, Chih-Kuang

doi:10.1016/j.ijheatmasstransfer.2006.06.044

Cited by 26 publications

(13 citation statements)

References 21 publications

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“…The fraction of specularly reflected/transmitted phonons at an interface, p, is used to characterize the roughness of the interfaces as usual. [4][5][6][7][8][9]14 Due to the full reflection at the heterogeneous interfaces, phonons in the layers possess a strong directional dependence. The existence of the heterogeneous interfaces also causes a nonuniform heat flux distribution.…”

Section: Methodsmentioning

confidence: 99%

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A Study of Phonon Transport in Si/Ge Superlattice Thin Films Using a Fast MC Solver

Huang

Tsai

Liu

2010

Journal of Elec Materi

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We employ a fast Monte Carlo solver, which takes advantage of the geometric symmetry existent in the system to reduce the computational effort, to investigate the phonon transport phenomena in the cross-plane and in-plane directions of Si/Ge superlattice thin films. The simulation results show that the heterogeneous interfaces perpendicular to the heat flow direction create a much stronger thermal resistance than the parallel ones. The cross-plane and in-plane thermal conductivities of a Si/Ge superlattice thin film increase monotonically with the smoothness of the interfaces and the superlattice period. Most of all, a minimum of the in-plane thermal conductivity is observed as the ratio of the layer thicknesses is varied for fixed period. This is due to the effective layer thermal conductivities being determined not only by the phonon intrinsic properties but also by the strong interface scattering. A detailed examination shows that the minimum appears when the effective layer thermal conductivities of the Si and Ge layers are about the same.

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Section: Methodsmentioning

confidence: 99%

“…Although many analytical methods [5][6][7][8] have been proposed to predict the thermal conductivity on the nanoscale, the analysis becomes intractable when the materials possess complicated nanostructures or are constituted of more than two materials. In this case, a simulation tool can be very useful.…”

Section: Introductionmentioning

confidence: 99%

A Study of Phonon Transport in Si/Ge Superlattice Thin Films Using a Fast MC Solver

Huang

Tsai

Liu

2010

Journal of Elec Materi

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“…silicon has a cubic structure. For continuum phonon calculations, the reader is referred to (Bannov et al 1995;Balandin and Wang 1998;Huang et al 2007). Molecular dynamics simulations of band folding or phonon confinement seem to concentrate on nanowires (Mingo 2003;Shiomi and Maruyama 2006).…”

Section: Dispersion By MDmentioning

confidence: 99%

Simulations of nanoscale thermal conduction

Heino

2008

Microsyst Technol

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In nanoscale, thermal conduction is affected by system size. Reasons are increased phonon scattering and changes in phonon group velocity. Computational modeling tools for thermal analysis have evolved in the past two decades. A brief overview of the state of the art is given. Nanoscale models can supply microscale computations with important parameters including relaxation times and group velocity. This work concentrates on group velocity and thermal conduction in thin silicon films. Changes in group velocity are addressed by calculating the dispersion relation with the molecular dynamics method, and for comparison, the conductivity is also directly computed. In all cases, the thermal resistivity increases as the film becomes thinner. Thermal conductivity is affected both by surface scattering and decreased group velocity. The group velocity changes both due to band folding and phonon confinement. The results indicate that in very thin films, the conductivity becomes highly anisotropic due to differences in surface scattering. In two low-index surfaces, the role of dispersion is only minor as compared to the role of surface scattering, while in one case, evidence of almost specular scattering was seen.

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“…[4][5][6] In all of these approaches, a specularity parameter is usually introduced to characterize the surface roughness or the strength of boundary scattering. To avoid those ad hoc models, nonequilibrium molecular dynamics (NEMD) simulation has been developed to evaluate the thermal conductivity of solid materials.…”

Section: Introductionmentioning

confidence: 99%

“…8,9 Low-dimensional materials nonetheless possess different phonon spectra due to the size confinement effect. 5,6 To the authors' knowledge, there had been no study taking the finite-size effect, the quantum correction, and the confined phonon spectra all into consideration, which constituted the motivation for this work.…”

Section: Introductionmentioning

confidence: 99%

A Nonequilibrium Molecular Dynamics Study of In-Plane Thermal Conductivity of Silicon Thin Films

Chang

Weng

Huang

2010

Journal of Elec Materi

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We employed a nonequilibrium molecular dynamics (NEMD) simulator to calculate the in-plane thermal conductivity of silicon thin films. To avoid contamination of the temperature nonlinearity due to artificial heat addition/ rejection, the selection of a proper linear range was investigated. It was found that the contaminated range was larger for thicker films and longer simulation lengths. To perform the quantum correction that is necessary when the MD simulation temperature is lower than the Debye temperature, we also attempted to obtain the confined phonon densities of states via equilibrium MD (EMD) simulations. The investigation showed that the thermal conductivities corrected by the thin-film density of states (DOS) agree excellently with theoretical predictions based on the phonon Boltzmann transport equation. A relationship between the surface roughness measurable in the laboratory and the specular fraction usually employed in the analysis was thus constructed.

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A new lattice thermal conductivity model of a thin-film semiconductor

Cited by 26 publications

References 21 publications

A Study of Phonon Transport in Si/Ge Superlattice Thin Films Using a Fast MC Solver

A Study of Phonon Transport in Si/Ge Superlattice Thin Films Using a Fast MC Solver

Simulations of nanoscale thermal conduction

A Nonequilibrium Molecular Dynamics Study of In-Plane Thermal Conductivity of Silicon Thin Films

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