Phonon Transport in Silicon Thin Film: Effect of Temperature Oscillation on Effective Thermal Conductivity

2013 ◽  
Vol 42 (4-5) ◽  
pp. 179-201 ◽  
Author(s):  
Saad Bin Mansoor ◽  
Bekir Sami Yilbas
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Temperature Oscillation ◽  
Phonon Transport ◽  
Effect Of Temperature ◽  
Silicon Thin Film

Phonon transport characteristics across silicon thin film pair: Presence of a gap between the films

2015 ◽  
Vol 40 (3) ◽  
Author(s):  
Haider Ali ◽  
Bekir S. Yilbas
Keyword(s):  
Thin Film ◽  
Experimental Data ◽  
Thermal Conductivity ◽  
Temperature Difference ◽  
Radiation Heat Transfer ◽  
Phonon Transport ◽  
Radiative Energy ◽  
Gap Size ◽  
Boltzmann Transport ◽  
Silicon Thin Film

AbstractPhonon transport across silicon thin film pair with minute gap (Casimir limit) between the films is studied. Phonon transport characteristics across the gap are examined for various gap sizes, and the transient solution of the frequency-dependent Boltzmann transport equation is presented according to relevant boundary conditions incorporating the gap between the film pair. Since the gap size is minute (Casimir limit), the radiative energy transport between the edges of the film pair is incorporated. In addition, phonon transmission and reflection is introduced at the gap edges, thus satisfying energy conservation. The thermal conductivity predicted is validated through experimental data reported in the open literature. Predicted thermal conductivity data agree well with the experimental data reported in the open literature. Increasing gap size alters the phonon transport characteristics across the film pair. Increasing gap size enhances temperature difference between the edges of the gap; in which case, the effect of phonon transmittance is more significant on the temperature difference than that corresponding to the radiation heat transfer due to Casimir limit.

Silicon Thin-Film Lattice Dynamics and Thermal Transport Properties

2012 ◽  
Author(s):  
Bruce L. Davis ◽  
Mehmet Su ◽  
Ihab El-Kady ◽  
Mahmoud I. Hussein
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Transport Properties ◽  
Lattice Dynamics ◽  
Dielectric Materials ◽  
Phonon Transport ◽  
Solid State Physics ◽  
Silicon Thin Film ◽  
Silicon Thin Films

Thin films composed of dielectric materials are attracting growing interest in the solid state physics and nanoscale heat transfer communities. This is primarily due to their unique thermal and electronic properties and their extensive use as components in optoelectronic, and potentially in thermoelectric, devices. In this paper, an elaborate study is presented on silicon thin films ranging from a few nanometers in thickness to very thick bulk-like thicknesses. Full lattice dynamics calculations are performed incorporating the entire film cross section and the relaxation of the free surfaces. The phonon properties emerging from these calculations are then incorporated into Holland-Callaway models to predict the thermal conductivity and other phonon transport properties. A rigorous curve fitting process to a limited set of available experimental data is carried out to obtain the scattering lifetimes. Our results demonstrate the importance of proper consideration of the full thin-film dispersion description and provide insights into the relationship between thermal conductivity, film thickness and temperature.

Influence of heat source size and film thickness on phonon transport in a two-dimensional thin film

2014 ◽  
Vol 39 (2) ◽  
Author(s):  
Haider Ali ◽  
Bekir S. Yilbas
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Heat Source ◽  
Film Thickness ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Phonon Transport ◽  
Source Size ◽  
Two Dimensional ◽  
Ballistic Phonons

Abstract.Phonon transport in a two-dimensional thin silicon film is considered and the effect of heat source size and the film thickness on the transport characteristics is examined. Frequency dependent Boltzmann equation is incorporated in the analysis to account for the contribution of the ballistic phonons to the energy transport. Equivalent equilibrium temperature is introduced to assess the thermal resistance during the phonon transport in the film. The numerical scheme with the appropriate boundary conditions is used to predict the transport properties, including the effective thermal conductivity, of the thin film. It is found that the heat source size and the film thickness influence the thermal resistance of the film almost equally. The ballistic phonons reduce the film thermal resistance while suppressing the effective thermal conductivity in the thin film.

Evaluation of the Temperature Oscillation Technique to Calculate Thermal Conductivity of Water and Systematic Measurement of the Thermal Conductivity of Aluminum Oxide – Water Nanofluid

2004 ◽  
Author(s):  
P. Bhattacharya ◽  
S. Nara ◽  
P. Vijayan ◽  
T. Tang ◽  
W. Lai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Aluminum Oxide ◽  
Effective Thermal Conductivity ◽  
Base Fluid ◽  
Suspended Solid ◽  
Temperature Oscillation ◽  
Solid Particles ◽  
Systematic Measurement ◽  
Experimental Setup ◽  
Suspended Solid Particles

A nanofluid is a fluid containing suspended solid particles, with sizes of the order of nanometers. The nanofluids are better conductors of heat than the base fluid itself. Therefore it is of interest to measure the effective thermal conductivity of such a nanofluid. We use temperature oscillation technique to measure the thermal conductivity of the nanofluid. However, first we evaluate the temperature oscillation technique as a tool to measure thermal conductivity of water. Then we validate our experimental setup by measuring the thermal conductivity of the aluminum oxide-water nanofluid and comparing our results with previously published work. Finally, we do a systematic series of measurements of the thermal conductivities of aluminum oxide-water nanofluids at various temperatures and explain the reasons behind the dependence of the enhancement in thermal conductivity of the nanofluid on temperature.

411 In-Plane Thermal Conductivity and Electrical Conductivity Measurements of Silicon Thin Film

2012 ◽  
Vol 2012.65 (0) ◽  
pp. 139-140
Author(s):  
Harutoshi HAGINO ◽  
Yosuke KAWAHARA ◽  
Aimi GOTO ◽  
Toru HIWADA ◽  
Koji Miyazaki
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Conductivity Measurements ◽  
Silicon Thin Film

Size and Interface Effects on Thermal Conductivity of Superlattices and Periodic Thin-Film Structures

1997 ◽  
Vol 119 (2) ◽  
pp. 220-229 ◽  
Author(s):  
G. Chen
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Amorphous Materials ◽  
High Efficiency ◽  
Interface Roughness ◽  
Atomic Scale ◽  
Diffuse Interface ◽  
Boltzmann Transport ◽  
Diffuse Interfaces

Superlattices consisting of alternating layers of extremely thin films often demonstrate strong quantum size effects that have been utilized to improve conventional devices and develop new ones. The interfaces in these structures also affect their thermophysical properties through reflection and transmission of heat carriers. This work develops models on the effective thermal conductivity of periodic thin-film structures in the parallel direction based on the Boltzmann transport equation. Different interface conditions including specular, diffuse, and partially specular and partially diffuse interfaces, are considered. Results obtained from the partially specular and partially diffuse interface scattering model are in good agreement with experimental data on GaAs/AlAs superlattices. The study shows that the atomic scale interface roughness is the major cause for the measured reduction in the superlattice thermal conductivity. This work also suggests that by controlling interface roughness, the effective thermal conductivity of superlattices made of bulk materials with high thermal conductivities can be reduced to a level comparable to those of amorphous materials, while maintaining high electrical conductivities. This suggestion opens new possibilities in the search of high efficiency thermoelectric materials.

Phonon Transport in a Thin Film due to Temperature Oscillation at the Film Edge

2015 ◽  
Vol 16 (7-8) ◽  
Author(s):  
H. Ali ◽  
B.S. Yilbas
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Heat Source ◽  
Oscillation Frequency ◽  
Coupling Effect ◽  
Equilibrium Temperature ◽  
Temperature Oscillation ◽  
Phonon Transport ◽  
Source Size ◽  
Temperature Disturbance

AbstractTransient response of phonon transport in a two-dimensional silicon thin film due to temperature disturbance at the film edge is investigated. Temperature oscillations with different frequencies are incorporated at the high-temperature edge of the film while uniform temperature is assumed initially in the film. The size of heat source, due to temperature oscillation, is varied at the film edge to investigate the coupling effect of oscillation frequency and the heat source size on the phonon transport in the film. Equivalent equilibrium temperature is introduced to assess the phonon transport characteristics for different temperature disturbance conditions. A numerical method incorporating the discrete ordinate method is used to solve the Boltzmann transport equation with the appropriate boundary conditions. It is found that equivalent equilibrium temperature oscillates in the region close to the high-temperature edge of the film; however, oscillation characteristics in terms of frequency and amplitude do not follow temperature oscillation at the film edge. Heat source size and oscillation frequency influence significantly equivalent equilibrium temperature in the film, which is more pronounced in the late heating periods.

scholarly journals Modeling of Thermoelectric Properties of Semi-Conductor Thin Films With Quantum and Scattering Effects

2006 ◽  
Vol 129 (4) ◽  
pp. 492-499 ◽  
Author(s):  
A. Bulusu ◽  
D. G. Walker
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Phonon Scattering ◽  
Quantum Effects ◽  
Effect Of Temperature ◽  
Fundamental Parameters ◽  
Scattering Effects ◽  
Electron Phonon Scattering

Several new reduced-scale structures have been proposed to improve thermoelectric properties of materials. In particular, superlattice thin films and wires should decrease the thermal conductivity, due to increased phonon boundary scattering, while increasing the local electron density of states for improved thermopower. The net effect should be increased ZT, the performance metric for thermoelectric structures. Modeling these structures is challenging because quantum effects often have to be combined with noncontinuum effects and because electronic and thermal systems are tightly coupled. The nonequilibrium Green’s function (NEGF) approach, which provides a platform to address both of these difficulties, is used to predict the thermoelectric properties of thin-film structures based on a limited number of fundamental parameters. The model includes quantum effects and electron-phonon scattering. Results indicate a 26–90 % decrease in channel current for the case of near-elastic, phase-breaking, electron-phonon scattering for single phonon energies ranging from 0.2 meV to 60 meV. In addition, the NEGF model is used to assess the effect of temperature on device characteristics of thin-film heterojunctions whose applications include thermoelectric cooling of electronic and optoelectronic systems. Results show the predicted Seebeck coefficient to be similar to measured trends. Although superlattices have been known to show reduced thermal conductivity, results show that the inclusion of scattering effects reduces the electrical conductivity leading to a significant reduction in the power factor (S2σ).

Size-Dependent Model for Thin Film Thermal Conductivity

2011 ◽  
Author(s):  
Alan J. H. McGaughey ◽  
Daniel P. Sellan ◽  
Eric S. Landry ◽  
Cristina H. Amon
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Classical Model ◽  
Relaxation Times ◽  
Silicon Thin Film ◽  
Size Dependent ◽  
Model Predictions ◽  
Dependent Model ◽  
Better Than ◽  
Phonon Properties

We present a closed-form classical model for the size dependence of thin film thermal conductivity. The model predictions are compared to Stillinger-Weber silicon thin film thermal conductivities (in-plane and cross-plane directions) calculated using phonon properties obtained from lattice dynamics calculations. By including the frequency dependence of the phonon-phonon relaxation times, the model is able to capture the approach to the bulk thermal conductivity better than models based on a single relaxation time.

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