Microscale Thermophysical Engineering

Tien, C. L.; Hijikata, Kunio; Peterson, G. P.; Majumdar, Alok

doi:10.1080/108939597200377

Cited by 59 publications

(95 citation statements)

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“…Alternatively, Lin's and Chen's models predicted that the electron-phonon relaxation time converges to 5 ps approximately. Considering that average electron-phonon relaxation time was a few picoseconds, 24,33) both models showed good agreement in predicting the relaxation time, and the use of constant electron-phonon coupling was no longer appropriate. Figure 6 presents electron and phonon temperatures at different times (0.1, 1, 5, 10, and 15 ps after irradiation).…”

Section: Comparison Of Theoretical Models Of Electron-phonon Couplingmentioning

confidence: 99%

“…The electron-electron collision time was approximately 1 fs and electron-phonon collision time was approximately 100 fs. 24) Since a thermal equilibrium requires 5-20 collisions between energy carriers, the electron-phonon relaxation time is $10 À12 s. 24,33) Thus, at a high laser fluence, the use of a constant electron-phonon coupling is no longer valid, but Chen's and Lin's models are appropriate for predicting energy transport between electrons and phonons. Figure 4 represents the predicted lattice temperature with respect to laser fluence at 1 ps after irradiation.…”

Section: Comparison Of Theoretical Models Of Electron-phonon Couplingmentioning

confidence: 99%

“…24) Because this Sommerfeld expansion is no longer valid for high electron temperatures, the electron heat capacity needs to be calculated from the following equation; 12) C e ðT e Þ ¼…”

Section: Mathematical Representation and Computational Detailsmentioning

confidence: 99%

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Comparison of Theoretical Models of Electron-Phonon Coupling in Thin Gold Films Irradiated by Femtosecond Pulse Lasers

2011

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This study reports on a comparison of theoretical models for electron-phonon coupling that is substantially associated with nonequilibrium energy transport in thin gold films irradiated by femtosecond pulse lasers. Three published electron-phonon coupling models were analyzed with the use of a well-established two-temperature model to describe non-equilibrium energy transport between electrons and phonons. Based on the numerical results, at lower fluence, all models showed nearly similar tendencies, whereas at higher fluence, constant electronphonon coupling forced unrealistically long electron-phonon equilibration times and spatially long diffusive regions as it failed to intrinsically consider the effect of a high number density of excited d-band electrons. Even at higher fluence, however, both Lin's and Chen's models yielded physically reasonable results, showing converging electron-phonon equilibration times and steep gradients in the spatial lattice temperature profiles at higher laser fluence. In particular, Lin's model predicts nonlinear characteristics of heat capacity and lattice temperature with respect to laser fluence better than Chen's model. Moreover, the electron-phonon relaxation time increased with laser fluence, whereas at laser fluence greater than 0.05 J/cm 2 , the thermal equilibrium time was nearly independent of the laser fluence. Thus, it was concluded that Lin's model better predicted the electron-phonon coupling phenomena in thin metal films irradiated by ultra-short pulse lasers.

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Section: Comparison Of Theoretical Models Of Electron-phonon Couplingmentioning

confidence: 99%

Section: Comparison Of Theoretical Models Of Electron-phonon Couplingmentioning

confidence: 99%

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Comparison of Theoretical Models of Electron-Phonon Coupling in Thin Gold Films Irradiated by Femtosecond Pulse Lasers

2011

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“…First, the electron heat capacity is commonly expressed as a linear function of the electron temperature, C e ðT e Þ ¼ T e , where ¼ % 2 n e k 2 B =2" F . 22) Because this Sommerfeld expansion is no longer valid for high electron temperatures, the electron heat capacity is calculated from the following equation:…”

Section: Numerical Modeling and Computational Detailsmentioning

confidence: 99%

Thermal Boundary Resistance Effect on Non-Equilibrium Energy Transport in Metal-Dielectric Thin Films Heated by Femtosecond Pulse Lasers

Lee

2011

Mater. Trans.

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The aim of this study is to investigate the effect of interfacial thermal boundary resistance (TBR) at a metal-dielectric interface on nonequilibrium energy transport in Au/SiO 2 films heated by femtosecond pulse lasers. In this paper we suggest a combined set of numerical models that include the two-temperature model (TTM) for a metal side and the heat conduction equation for a dielectric layer. In addition, the TBRs between metal and nonmetal layers are calculated using thermal conductance, which is closely associated with the electron-phonon resistance and phonon-phonon resistance. Herein we present the transient and spatial distributions of TBR for a Au/SiO 2 film irradiated by a 100-fs pulse laser with a 1053 nm wavelength, which are substantially affected by the phonon temperature and electron-phonon coupling. We also discuss the effect of laser fluence on the TBR and energy transport. The TBR rapidly increases the thermal conductivity at the interface, and becomes dominant at an early stage of laser irradiation over a very short period and then drastically decreases with time. Moreover, the TBR is substantially affected by the electron-phonon coupling and it should be considered for more accurate prediction of the lattice temperature drop at the interface.

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“…[1][2][3] In addition, the relatively slow decay process of optical phonons to acoustic phonons leads to a phonon bottleneck in the energy dissipation processes according to a number of theoretical studies. [4][5][6][7] However, there have been few direct experimental observations of such highly non-equilibrium transport processes. 8,9 Direct measurements are needed for better understanding the coupling and non-equilibrium transport processes of different energy carriers in semiconductors and for designing nextgeneration electronic devices to overcome the thermal management challenge.…”

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confidence: 99%

Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

Olsson

Klimovich

et al. 2015

Applied Physics Letters

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Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons.

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Microscale Thermophysical Engineering

Cited by 59 publications

References 0 publications

Comparison of Theoretical Models of Electron-Phonon Coupling in Thin Gold Films Irradiated by Femtosecond Pulse Lasers

Comparison of Theoretical Models of Electron-Phonon Coupling in Thin Gold Films Irradiated by Femtosecond Pulse Lasers

Thermal Boundary Resistance Effect on Non-Equilibrium Energy Transport in Metal-Dielectric Thin Films Heated by Femtosecond Pulse Lasers

Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

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