Mean free path of THz phonons in aluminum films

Mrzyglod, A.; Weis, O.

doi:10.1007/bf00752919

Cited by 6 publications

(5 citation statements)

References 10 publications

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“…We multiply these by v Al to find ph (100 GHz) ∼ = 1.04 µm, ph (400 GHz) ∼ = 0.38 µm and ph (700 GHz) ∼ = 0.22 µm. While these values are greater than some reported experimental values of ph in Al at energyhω = 2 e , they are comparable with measured values of normalstate acoustic attenuation corrected to the [31][32][33][36][37][38] superconducting state. Averaging equation (2) over our full Al layer thicknesses, we estimate that in the direction pointing out toward the detector, ∼90% of phonons at ω/2π = 100 GHz will escape into the Si, ∼78% at ω/2π = 400 GHz and ∼68% at ω/2π = 700 GHz.…”

Section: Modeling the Phonon Emission Spectrumsupporting

confidence: 82%

Design and operation of a microfabricated phonon spectrometer utilizing superconducting tunnel junctions as phonon transducers

et al. 2013

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In order to fully understand nanoscale heat transport it is necessary to spectrally characterize phonon transmission in nanostructures. Toward this goal we have developed a microfabricated phonon spectrometer. We utilize microfabricated superconducting tunnel junction (STJ)-based phonon transducers for the emission and detection of tunable, non-thermal and spectrally resolved acoustic phonons, with frequencies ranging from ∼100 to ∼870 GHz, in silicon microstructures. We show that phonon spectroscopy with STJs offers a spectral resolution of ∼15-20 GHz, which is ∼20 times better than thermal conductance measurements, for probing nanoscale phonon transport. The STJs are Al-Al x O y -Al tunnel junctions and phonon emission and detection occurs via quasiparticle excitation and decay transitions that occur in the superconducting films. We elaborate on the design geometry and constraints of the spectrometer, the fabrication techniques and the low-noise instrumentation that are essential for successful application of this technique for nanoscale phonon studies. We discuss the spectral distribution of phonons emitted by an STJ emitter and the 3 Current address:

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Section: Modeling the Phonon Emission Spectrumsupporting

confidence: 82%

Design and operation of a microfabricated phonon spectrometer utilizing superconducting tunnel junctions as phonon transducers

et al. 2013

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“…37 Umklapp scattering of Al phonons will negligibly contribute to the thermal resistance in this interfacial region since the three phonon mean-free path in Al is orders of magnitude larger than ␦ at room temperature. 38 Therefore, Al,int,j = ͑ gb 4 . The Al phonon-scattering rate with Si atoms takes the familiar form derived by Klemens.…”

Section: ͑4͒mentioning

confidence: 99%

Effects of surface roughness and oxide layer on the thermal boundary conductance at aluminum/silicon interfaces

et al. 2010

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In nanosystems, the primary scattering mechanisms occur at the interfaces between the material layers. As such, the structure and composition around these interfaces can affect scattering rates and, therefore, thermal resistances. In this work, we measure the room-temperature thermal boundary conductance of aluminum films grown on silicon substrates subjected to various pre-Al-deposition surface treatments with a pump-probe thermoreflectance technique. The Si surfaces are characterized with atomic force microscopy to determine mean surface roughness. The measured thermal boundary conductances decrease as Si surface roughness increases. In addition, stripping of the native oxide layer from the surface of the Si substrate immediately prior to Al film deposition causes the thermal boundary conductance to increase. The measured data are compared to an extension of the diffuse mismatch model that accounts for interfacial mixing and structure around the interface in order to better elucidate the thermal scattering processes affecting thermal boundary conductance at rough interfaces.

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“…where p t is the probability for a phonon to be transmitted from the substrate to MKID, α is the fraction of the total inductance of the resonators due to kinetic inductance, λ pb is the mean free path for phonons to break Cooper pairs in the MKID 16,17 , and N 0 is the single-spin density of states. The ratio of the frequency to dissipation response is defined as β, while S 1 is a dimensionless factor of order unity describing the dissipation response at temperature, T 18,19 .…”

mentioning

confidence: 99%

Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors

Moore

Golwala

Bumble

et al. 2012

Applied Physics Letters

114

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We demonstrate position and energy-resolved phonon-mediated detection of particle interactions in a silicon substrate instrumented with an array of microwave kinetic inductance detectors (MKIDs). The relative magnitude and delay of the signal received in each sensor allows the location of the interaction to be determined with 1 mm resolution at 30 keV. Using this position information, variations in the detector response with position can be removed, and an energy resolution of σ E = 0.55 keV at 30 keV was measured. Since MKIDs can be fabricated from a single deposited film and are naturally multiplexed in the frequency domain, this technology can be extended to provide highly-pixelized athermal phonon sensors for ∼1 kg scale detector elements. Such high-resolution, massive particle detectors would be applicable to rare-event searches such as the direct detection of dark matter, neutrinoless double-beta decay, or coherent neutrino-nucleus scattering.Next generation rare-event searches such as the direct detection of dark matter require large target masses (∼10 3 kg) with sub-keV energy resolution. This requires increasing the mass of current solid-state, cryogenic experiments 1,2 by 2 orders of magnitude, while maintaining the background-free operation of existing detectors. Reducing the cost and time needed to fabricate and test each detector element is necessary for such large cryogenic experiments to be feasible.Detectors that measure both the athermal phonons and ionization created by a particle interaction have demonstrated sufficient background rejection to enable next-generation experiments 3 . Microwave kinetic inductance detectors (MKIDs) 4,5 offer several advantages for providing athermal phonon sensors in large experiments relative to the transition edge sensor (TES)-based designs currently in use 1,2,6 . MKIDs can be patterned from a single deposited aluminum film, with large (>10 µm) features, significantly reducing fabrication time and complexity. Since MKIDs are naturally multiplexed in the frequency domain, hundreds of sensors can be read out on a single coaxial cable, enabling a more granular phonon sensor that is expected to provide enhanced background rejection. In addition to dark matter direct detection, high-resolution, massive particle detectors are applicable to the detection of neutrinoless double-beta decay 7 and coherent neutrino-nucleus scattering 8 .Previous designs 9-11 attempted to absorb the incident energy in large-area collectors coupled to smaller volume, distributed MKIDs. Although separating the absorber and sensor allowed increased sensitivity by concentrating the absorbed energy, test devices suffered from poor transmission of quasiparticles from the absorber to sensor. Here we present a simplified design that eliminates the absorber by directly collecting the energy using large-area MKIDs. A similar design developed independently by Swenson et al. 12 has been used a) Electronic mail: davidm@caltech.edu to demonstrate time-resolved phonon-mediated detection of high-energy int...

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Mean free path of THz phonons in aluminum films

Cited by 6 publications

References 10 publications

Design and operation of a microfabricated phonon spectrometer utilizing superconducting tunnel junctions as phonon transducers

Design and operation of a microfabricated phonon spectrometer utilizing superconducting tunnel junctions as phonon transducers

Effects of surface roughness and oxide layer on the thermal boundary conductance at aluminum/silicon interfaces

Position and energy-resolved particle detection using phonon-mediated microwave kinetic inductance detectors

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