Entropy generation in silicon thin film: Influence of film thickness on entropy generation rate

Laser short-pule irradiation of silicon-diamond-aluminum thin lms is considered and energy transport across the lms is modelled using the Boltzmann transport equation. Electron-phonon coupling is adopted to formulate energy transfer across the electron and lattice sub-systems in the aluminum lm. Thermal boundary resistance is incorporated at the lm interfaces. The transfer matrix method is used to account for the transmittance, re ection and absorption of the incident laser radiation across the lms. Equivalent equilibrium temperature is introduced to access energy transport in the lms, which represents the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. It is found that equivalent equilibrium temperature increases sharply in the electron sub-system due to electron excess energy gain from the irradiated eld. Equivalent equilibrium temperature decays gradually in the lattice sub-system with increasing period due to phonon scattering in the lm.

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“…The values of the parameters used in (2) are listed at the end of Table 1. In the heat source term above, Tr is the transmittance, i.e.…”

Section: Equation Of Phonon Radiative Transfermentioning

confidence: 99%

“…Considerable research studies were carried out to examine energy transport in thin lms and laser beam interaction and energy transport at micro/nano scales [2][3][4][5][6][7][8][9][10][11]. A review on ultra-short laser interaction with matter was presented by Gamaly and Rode [12].…”

Section: Introductionmentioning

confidence: 99%

Thermal transport across a thin film composite due to laser short-pulse heating

Mansoor

Yilbaş

2015

Journal of Non-Equilibrium Thermodynamics

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“…They formulated the expression for the volumetric entropy generation rate in a one-dimensional, thin film and then used it to compute the entropy generation rate for various values of the Knudsen numbers. Ali and Yilbas [7] has also explored the phenomenon of entropy generation in thin films with thickness of the order of the mean free path of the phonon carriers. They studied the effect of changing the film thickness on the entropy generation rate.…”

Section: Introductionmentioning

confidence: 99%

Entropy Generation Rate in a Microscale Thin Film

Mansoor¹

2019

Journal of Thermal Engineering

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This paper presents a new formulation of the rate of entropy generation in thin films whose thickness is of the order of the mean-free-path or less. In this relation, an expression for the gradient of the equivalent equilibrium temperature is proposed that is a function of the gradient of the phonon intensity at any point inside the thin film. It is shown that the proposed expression reduces to the familiar gradient of the thermodynamic temperature in the diffusive limit. Furthermore, the new formulation is used to compute the entropy generation rate for the case of steady-state, one-dimensional heat transfer in a thin film by first solving the Equation of Phonon Radiative Transfer to determine the phonon intensity. These computations are performed both for the silicon and the diamond thin films, for a range of Knudsen numbers starting from the diffusive limit up until the ballistic limit. It is found that the entropy generation rate attains a peak value at Kn = 0.7 and decreases for other Knudsen numbers when non-equilibrium transport is adopted in the analysis. However, rate of entropy generation increases almost linearly for the equilibrium heating situation. This is true for both the silicon and the diamond thin films.

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“…The energy transport characteristics in thin lms are investigated analytically [20,21] and numerically [22][23][24][25][26]. Even transient phonon cross-plane transport that incorporates frequency dependence in thin silicon lm pair was investigated previously [1,27]; however, the e ect of gap length located between the lm pair was left for a future study.…”

Section: Introductionmentioning

confidence: 99%

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

Ali¹,

Yilbaş²

2015

Journal of Non-Equilibrium Thermodynamics

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Phonon transport across silicon thin lm pair with minute gap (Casimir limit) between the lms 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 lm pair. Since the gap size is minute (Casimir limit), the radiative energy transport between the edges of the lm pair is incorporated. In addition, phonon transmission and re ection 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 lm pair. Increasing gap size enhances temperature di erence between the edges of the gap; in which case, the e ect of phonon transmittance is more signi cant on the temperature di erence than that corresponding to the radiation heat transfer due to Casimir limit.

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Entropy generation in silicon thin film: Influence of film thickness on entropy generation rate

Cited by 9 publications

References 21 publications

Thermal transport across a thin film composite due to laser short-pulse heating

Thermal transport across a thin film composite due to laser short-pulse heating

Entropy Generation Rate in a Microscale Thin Film

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

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