Thermal conductivity of thin films: Measurements and understanding

Cahill, David G.; Fischer, Henry E.; Klitsner, T.; Swartz, Ed; Pohl, Robert Wichard

doi:10.1116/1.576265

Cited by 287 publications

(121 citation statements)

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“…Another very direct and intuitive approach is to run nonequilibrium molecular dynamics (MD) simulations, depositing energy into one vibrational mode and following its flow through the protein directly as a function of time (5-10). On the experimental side, the study of energy and heat transport is well established for bulk systems (solids, glasses, or liquids) (11). For proteins, however, essentially nothing is known about heat diffusion from experiment.…”

mentioning

confidence: 99%

Energy transport in peptide helices

Botan

Backus

Pfister

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

189

327

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We investigate energy transport through an ␣-aminoisobutyric acid-based 310-helix dissolved in chloroform in a combined experimental-theoretical approach. Vibrational energy is locally deposited at the N terminus of the helix by ultrafast internal conversion of a covalently attached, electronically excited, azobenzene moiety. Heat flow through the helix is detected with subpicosecond time resolution by employing vibrational probes as local thermometers at various distances from the heat source. The experiment is supplemented by detailed nonequilibrium molecular dynamics (MD) simulations of the process, revealing good qualitative agreement with experiment: Both theory and experiment exhibit an almost instantaneous temperature jump of the reporter units next to the heater which is attributed to the direct impact of the isomerizing azobenzene moiety. After this impact event, helix and azobenzene moiety appear to be thermally decoupled. The energy deposited in the helix thermalizes on a subpicosecond timescale and propagates along the helix in a diffusive-like process, accompanied by a significant loss into the solvent. However, in terms of quantitative numbers, theory and experiment differ. In particular, the MD simulation seems to overestimate the heat diffusion constant (2 Å 2 ps ؊1 from the experiment) by a factor of five.energy dissipation ͉ time-resolved IR spectroscopy ͉ peptide helix ͉ nonequilibrium molecular dynamics simulation

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mentioning

confidence: 99%

Energy transport in peptide helices

Botan

Backus

Pfister

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

189

327

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“…The thermal properties needed to know for the simulations are material thermal conductivities. In our experiments, the thermal conductivities of ErAr/InGaAs, SiO 2 , and SiN were measured using 3ω method 5,6 . Our thermal simulation results show that the temperature difference ratio of ∆T SL /∆T for our devices is around 0.5, thus the cross-plane Seebeck coefficients for sample 1, 2, 3 and 4 are 405.32 µV/K, 326.04 µV/K, 265.75 µV/K and 232.40 µV/K respectively.…”

Section: Resultsmentioning

confidence: 99%

ErAs/InGaAs superlattice Seebeck coefficient

Zeng

Bowers

Zhang

et al. 2005

ICT 2005. 24th International Conference on Thermoelectrics, 2005.

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InGaAs with embedded ErAs nano-particles is a promising material for thermoelectric applications. The incorporation of erbium arsenide metallic nanoparticles into the semiconductor can provide both charge carriers and create scattering centers for phonons. Electron filtering by heterostructure barriers can also enhance Seebeck coefficient by selective emission of hot electrons.2.1µm-thick ErAs/InGaAs superlattices with a period of 10 nm InAlGaAs and 20 nm InGaAs were grown using molecular beam epitaxy, and the effective doping is from 2x10 18 to 1x10 19 cm - 3. Special device patterns were developed for the measurement of the cross-plane Seebeck coefficient of the superlattice layers.. Using these device patterns, the combined Seebeck coefficient of superlattice and the substrate were measured and the temperature drops through the superlattice and InP substrate were determined with 3D ANSYS  simulations. The Seebeck coefficient of the superlattice layers is obtained based on the measurements and simulation results.

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“…Thermoreflectance may be used for noncontact characterization of thin-film thermal conductivity [9], [20]. In the 3ω method, an alternating current is applied to the heater/sample/sensor structure, and a lock-in amplifier is used to detect the current or voltage output signal at a particular frequency [1], [11], [14]. Another well-known method is based on steady-state joule heating with dc current excitation [9].…”

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confidence: 99%

Thin-Film Thermal Conductivity Measurement Using Microelectrothermal Test Structures and Finite-Element-Model-Based Data Analysis

Stojanović

Yun

Washington

et al. 2007

J. Microelectromech. Syst.

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Abstract-We present a new method for measuring thermal conductivities of films with nanoscale thickness. The method combines a microelectrothermal test structure with a finite-elementbased data analysis procedure. The test device consists of two serpentine nickel structures, which serve as resistive heaters and resistance temperature detectors, on top of the sample. The sample is supported by a silicon nitride membrane. Analytical solution of the heat flow is infeasible, making interpretation of the data difficult. To address this, we use a finite-element model of the test structure and apply nonlinear least-squares estimation to extract the desired material parameter values. The approach permits simultaneous extraction of multiple parameters. We demonstrate our technique by simultaneously obtaining the thermal conductivity of a 280 µm× 80 µm× 140 nm thick aluminum sample and the 360 µm× 160 µm× 180 nm thick silicon nitride support membrane. The thermal conductivity measured for the silicon nitride thin film is 2.1 W/mK, which is in agreement with reported values for films of this thickness. The thermal conductivity of the Al thin film is found to be 94 W/mK, which is significantly lower than reported bulk values and consistent both with reported trends for thin metallic films and with values that were obtained using electrical resistivity measurements and the WiedemannFranz law.[

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Thermal conductivity of thin films: Measurements and understanding

Cited by 287 publications

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Energy transport in peptide helices

Energy transport in peptide helices

ErAs/InGaAs superlattice Seebeck coefficient

Thin-Film Thermal Conductivity Measurement Using Microelectrothermal Test Structures and Finite-Element-Model-Based Data Analysis

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