Ab initio determination of effective electron–phonon coupling factor in copper

Ji, Pengfei; Zhang, Kun

doi:10.1016/j.physleta.2016.02.044

Cited by 21 publications

(19 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Optical penetration depth of the pump (523 nm) in Cu is 33 nm, so we can assume that all the heat is absorbed by the Cu layer. Electron-phonon coupling time for Cu is less than 30 picoseconds, which should not affect our experiment [33]. Figure 2 (a) shows the results for the 220-nm-thick Cu nano-film, for which two different grating periods (λ ¼ 10 μm and 20 μm) are used, and the temperature rise at the sample surface is estimated to be lower than 9 K. Because the pump and probe beams are modulated in the same way, the probe beam only senses the area heated by the pump (green lines in Figure 1b).…”

Section: Resultsmentioning

confidence: 87%

In-plane Thermal Conductivity Measurement with Nanosecond Grating Imaging Technique

Jeong

Walker

et al. 2017

Nanoscale and Microscale Thermophysical Engineering

View full text Add to dashboard Cite

We develop a nanosecond grating imaging (NGI) technique to measure inplane thermal transport properties in bulk and thin-film samples. Based on nanosecond time-domain thermoreflectance (ns-TDTR), NGI incorporates a photomask with periodic metal strips patterned on a transparent dielectric substrate to generate grating images of pump and probe lasers on the sample surface, which induces heat conduction along both cross-and inplane directions. Analytical and numerical models have been developed to extract thermal conductivities in both bulk and thin-film samples from NGI measurements. This newly developed technique is used to determine thickness-dependent in-plane thermal conductivities (κ x) in Cu nano-films, which agree well with the electron thermal conductivity values converted from four-point electrical conductivity measurements using the Wiedemamn-Franz law, as well as previously reported experimental values. The κ x measured with NGI in an 8 nm x 8 nm GaAs/AlAs superlattice (SL) is about 10.2 W/m⋅K, larger than the cross-plane thermal conductivity (8.8 W/m⋅K), indicating the anisotropic thermal transport in the SL structure. The uncertainty of the measured κ x is about 25% in the Cu film and less than 5% in SL. Sensitivity analysis suggests that, with the careful selection of proper substrate and interface resistance, the uncertainty of κ x in Cu nanofilms can be as low as 5%, showing the potential of the NGI technique to determine κ x in thin films with improved accuracy. By simply installing a photomask into ns-TDTR, NGI provides a convenient, fast, and cost-effective method to measure the in-plane thermal conductivities in a wide range of structures and materials.

show abstract

Section: Resultsmentioning

confidence: 87%

In-plane Thermal Conductivity Measurement with Nanosecond Grating Imaging Technique

Jeong

Walker

et al. 2017

Nanoscale and Microscale Thermophysical Engineering

View full text Add to dashboard Cite

show abstract

“…Besides the QM modeling of in the present work, the electron heat capacity [19] and the electron-phonon coupling factor were also determined from QM modeling [20] 〈 〉 , 7…”

Section: Modeling and Simulationmentioning

confidence: 99%

Multiscale modeling of femtosecond laser irradiation on a copper film with electron thermal conductivity from ab initio calculation

Zhang

2017

Numerical Heat Transfer, Part A: Applications

Self Cite

View full text Add to dashboard Cite

By combining ab initio quantum mechanics calculation and Drude model, electron temperature and lattice temperature dependent electron thermal conductivity is calculated and implemented into a multiscale model of laser material interaction, which couples the classical molecular dynamics and two-temperature model. The results indicated that the electron thermal conductivity obtained from ab initio calculation leads to faster thermal diffusion than that using the electron thermal conductivity from empirical determination, which further induces deeper melting region, larger number of density waves travelling inside the copper film and more various speeds of atomic clusters ablated from the irradiated film surface.

show abstract

“…The QM-MD-TTM integrated framework is constructed by combing Eqs. (1), (2), (5), (6) and (10). The simulation code is developed as an extension of the TTM part in the IMD [38] and the ABINIT [39].…”

Section: Simulation Detailsmentioning

confidence: 99%

“…When 0.5 10 , there are overlaps among three computed by using different methods, which implicitly demonstrates the number of excited electron is only 5 . When continues increasing from 0.5 10 to higher values, the 4 electrons get excited as a result of breakdown of the linear relationship between and , as well as the redistribution of . Due to the left shift of to lower and narrowing theband distribution, the term | ⁄ | in Eq.…”

Section: Electron Thermophysical Parameters Andmentioning

confidence: 99%

Melting and thermal ablation of a silver film induced by femtosecond laser heating: a multiscale modeling approach

Zhang

2017

Appl. Phys. A

Self Cite

View full text Add to dashboard Cite

The femtosecond laser pulse heating of silver film is investigated by performing quantum mechanics (QM), molecular dynamics (MD) and two temperature model (TTM) integrated multiscale simulation. The laser excitation dependent electron thermophysical parameters (electron heat capacity, electron thermal conductivity, and effective electron-phonon coupling factor) are determined from ab initio QM calculation, and implemented into TTM description of electron thermal excitation, heat conduction, as well as electron-phonon coupled thermal energy transport. The kinetics of atomic motion is modeled by MD simulation. Energy evolution of excited electron subsystem is described by TTM in continuum. The MD and TTM are coupled by utilizing the effective electron-phonon coupling factor. Laser heating with varying laser fluence is systematically studied to determine the thresholds of the homogeneous melting and ablation. The thermal ablation induced by faster expansion of locally and excessively superheated silver is reported. This paper provides a basis for interpreting the phase change process induced by laser heating, and facilitates the advancement of femtosecond laser pulse processing of material.

show abstract

Ab initio determination of effective electron–phonon coupling factor in copper

Cited by 21 publications

References 26 publications

In-plane Thermal Conductivity Measurement with Nanosecond Grating Imaging Technique

In-plane Thermal Conductivity Measurement with Nanosecond Grating Imaging Technique

Multiscale modeling of femtosecond laser irradiation on a copper film with electron thermal conductivity from ab initio calculation

Melting and thermal ablation of a silver film induced by femtosecond laser heating: a multiscale modeling approach

Contact Info

Product

Resources

About