Phonon attenuation in the GHz regime: Measurements and simulations with a visco-elastic material model

Bryner, J.; Kehoe, Timothy; Vollmann, J.; Aebi, L.; Wenke, Ingo; Dual, Jürg

doi:10.1016/j.phpro.2010.01.045

Cited by 9 publications

(4 citation statements)

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“…[2], when wealso neglectthe attenuation in Al. The damping we obtain for polycrystalline Al is in good agreement with the results from Bryner et al [31], and the values for the damping in Si are in good agreement with the findings of Cuffe et al [11]. Our results show that thisusual approach, whichneglectsacoustic damping, can cause considerable deviations inthe interfacial adhesion, and should thus be included in the modeling when quantitative measurements are aimed for.…”

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Characterization of thin-film adhesion and phonon lifetimes in Al/Si membranes by picosecond ultrasonics

Großmann

Schubert

et al. 2017

New J. Phys.

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We quantitatively study interfacial adhesion in a two-layer membrane system consisting of Al and Si with femtosecond time-resolved laser spectroscopy. High-frequency acoustic pulses in the sub-THz regime are utilized to characterize the membrane system. In order to explain the distinct features of the measured data, a spring model for the Al/Si interface is employed. We show that acoustic dissipation in this system needs to be included for accurate modeling of the interface adhesion over a broad frequency range. This modeling approach yields a spring constant of h = -17 Al Si -kg nm s 2 2 , an acoustic phonon lifetime of t = 68 Al ps at 240 GHz in polycrystalline Al and a frequency dependence of the lifetime in Si w µ -1 in thefrequency range from 50-800 GHz.Heat dissipation in Si is central to the operation of semiconductor devices [1-3]. This becomes even morechallengingdue to the miniaturization of all components as the contribution ofthe boundaries to phonon scattering becomes larger [4][5][6]. The question of understanding and controlling thermal phonons is of major interest [7][8][9]. Quantitative values forintrinsic phonon-phonon scattering processes and extrinsic scattering processes due to defects and surface/interface roughness are still under investigation [10][11][12]. While there exista wide variety of tools for the spatial mapping of temperature [13,14], there are not many temporal techniques for measuring nonequilibrium heat transport. One way is to look at coherent acoustic phonons at frequencies that contributeto the spectrum of thermal phonons [15]. Picosecond laser ultrasonics [16,17] is known to bea powerful tool for the characterization of the elastic properties of thin films. Sub-nanometer thick interfacial layers separating thin films from the substrate can influence both the decay time of the thin film vibration [18] and propagation of the coherent acoustic pulses [19]. Later it was demonstrated thatthe quantitative evaluation of the thickness of broad interfacial layers [20][21][22][23][24] and the rigidity of thin interfacial bonds [2, 25-29] can be obtained. Here, we study interfacial adhesion as well as damping behaviorin two-layer Al/Si-membranes. As a quantitative measure for the interface adhesion, the spring constant of a massless spring model is determined [25].The investigated system is a 13 nm thick Al film on top of a 350 nm thick Si membrane (see figure 1(a)). Details regarding the fabrication of the membrane are given in [27]. In [27], Al films with different thicknesses were fabricated by sputtering deposition on the membranes, which led tostrong adhesion between both layers. Here, in contrastto this approach, the Al film was thermally evaporated,resultingin reduced interface adhesion. The measurements were conducted with an 800 MHz Ti:sapphire pump-probe setup, utilizing the asynchronous optical sampling principle. Further details regarding the setup are given in [27,30]. We impulsively excite the Al film with an fs-laser pump pulse (30 mW power, 790 nm wave...

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confidence: 91%

Characterization of thin-film adhesion and phonon lifetimes in Al/Si membranes by picosecond ultrasonics

Großmann

Schubert

et al. 2017

New J. Phys.

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“…A visco-elastic model 19 is applied to simulate the frequency dependence of the observed damping times. The material properties of the gold film and the silicon substrate are kept constant for all frequencies.…”

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Modification of vibrational damping times in thin gold films by self-assembled molecular layers

Hettich

Bruchhausen

Riedel

et al. 2011

Applied Physics Letters

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Published by the AIP Publishing Articles you may be interested inEffect of fluorocarbon self-assembled monolayer films on sidewall adhesion and friction of surface micromachines with impacting and sliding contact interfaces Measurement of stiffness and damping constant of self-assembled monolayers Rev. Sci. Instrum. 76, 035102 (2005); 10.1063/1.1857278Patterning of gold film on muscovite mica by using a helium-metastable atom beam and an octanethiol selfassembled monolayer

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“…The density and the transverse speed of sound of metals are of the orders of 10 4 kg/m 3 and 10 3 m s −1 , respectively. The viscosity of solids is a quantity which is not easily accessible, but it may be estimated to range between 0.1 ∼ 1 Pa s for copper (at 2 kHz) and steel (at 5 MHz) [65], and 0.01 Pa s for aluminum (at 50 GHz) [66]. Notice that we infer the estimated values of viscosity from the measures of sound attenuation since directly measuring viscosity of metals below the melting temperatures is very difficult.…”

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confidence: 98%

Noncontact friction: Role of phonon damping and its nonuniversality

Lee,

Vink,

Volkert

et al. 2021

Preprint

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While obtaining theoretical predictions for dissipation during sliding motion is a difficult task, one regime that allows for analytical results is the so-called noncontact regime, where a probe is weakly interacting with the surface over which it moves. Studying this regime for a model crystal, we extend previously obtained analytical results and confirm them quantitatively via particle based computer simulations. Accessing the subtle regime of weak coupling in simulations is possible via use of Green-Kubo relations. The analysis allows to extract and compare the two paradigmatic mechanisms that have been found to lead to dissipation: phonon radiation, prevailing even in a purely elastic solid, and phonon damping, e.g., caused by viscous motion of crystal atoms. While phonon radiation is dominant at large probe-surface distances, phonon damping dominates at small distances. Phonon radiation is furthermore a pairwise additive phenomenon so that the dissipation due to interaction with different parts (areas) of the surface adds up. This additive scaling results from a general one-to-one mapping between the mean probe-surface force and the friction due to phonon radiation, irrespective of the nature of the underlying pair interaction. In contrast, phonon damping is strongly non-additive, and no such general relation exists. We show that for certain cases, the dissipation can even decrease with increasing surface area the probe interacts with. The above properties, which are rooted in the spatial correlations of surface fluctuations, are expected to have important consequences when interpreting experimental measurements, as well as scaling with system size.

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Phonon attenuation in the GHz regime: Measurements and simulations with a visco-elastic material model

Cited by 9 publications

References 5 publications

Characterization of thin-film adhesion and phonon lifetimes in Al/Si membranes by picosecond ultrasonics

Characterization of thin-film adhesion and phonon lifetimes in Al/Si membranes by picosecond ultrasonics

Modification of vibrational damping times in thin gold films by self-assembled molecular layers

Noncontact friction: Role of phonon damping and its nonuniversality

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