Evidence for the alteration of an organic/metal interface resulting from the formation of a broad interfacial layer

Bonello, Bernard; Armand, F.; Pradeau, J P; Pérez, H.; Perrin, Bernard; Louis, G.

doi:10.1063/1.371466

Cited by 12 publications

(6 citation statements)

References 20 publications

(15 reference statements)

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“…The interlayer phonon modes in 2D nanolayers have been studied using Raman scattering 12 . However, the bonds may not be perfect across the whole area of the nanolayer; in this case an effective way to study them is to monitor the nanomechanical vibrations of the sandwiched nanostructure 13 14 15 16 . Two dimensional (2D) nanolayers possess nanomechanical (i.e.…”

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confidence: 99%

Nanomechanical probing of the layer/substrate interface of an exfoliated InSe sheet on sapphire

Beardsley

Akimov

Greener

et al. 2016

Sci Rep

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Van der Waals (vdW) layered crystals and heterostructures have attracted substantial interest for potential applications in a wide range of emerging technologies. An important, but often overlooked, consideration in the development of implementable devices is phonon transport through the structure interfaces. Here we report on the interface properties of exfoliated InSe on a sapphire substrate. We use a picosecond acoustic technique to probe the phonon resonances in the InSe vdW layered crystal. Analysis of the nanomechanics indicates that the InSe is mechanically decoupled from the substrate and thus presents an elastically imperfect interface. A high degree of phonon isolation at the interface points toward applications in thermoelectric devices, or the inclusion of an acoustic transition layer in device design. These findings demonstrate basic properties of layered structures and so illustrate the usefulness of nanomechanical probing in nanolayer/nanolayer or nanolayer/substrate interface tuning in vdW heterostructures.

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confidence: 99%

Nanomechanical probing of the layer/substrate interface of an exfoliated InSe sheet on sapphire

Beardsley

Akimov

Greener

et al. 2016

Sci Rep

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“…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.…”

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confidence: 99%

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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“…10 Several investigations have already been carried out on the elastic properties of ultrathin polymer films with this method. [11][12][13][14][15][16][17][18][19] In our study, we image an embedded and patterned self-assembled organic layer sandwiched between a gold film and a silicon substrate by the damping time of the capping gold layer oscillation. We also utilize the time offset of the so called Brillouin oscillation originating from the silicon substrate to image the structure and to estimate the organic layer thickness.…”

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confidence: 99%

Imaging of a patterned and buried molecular layer by coherent acoustic phonon spectroscopy

Hettich

Jacob

Ristow

et al. 2012

Applied Physics Letters

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Influence of crystallographic orientation and anisotropy on Kapitza conductance via classical molecular dynamics simulations J. Appl. Phys. 112, 093515 (2012) Pulsed terahertz radiation due to coherent phonon-polariton excitation in 110 ZnTe crystal J. Appl. Phys. 112, 093110 (2012) Dynamical thermal conductivity of bulk semiconductor crystals J. Appl. Phys. 112, 083515 (2012) Influences of lattice vibration and electron transition on thermal emissivity of Nd3+ doped LaMgAl11O19 hexaaluminates for metallic thermal protection system Appl. Phys. Lett. 101, 161903 (2012) Phonon dynamics in CuxBi2Se3 (x=0, 0.1, 0.125) and Bi2Se2 crystals studied using femtosecond spectroscopy

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Evidence for the alteration of an organic/metal interface resulting from the formation of a broad interfacial layer

Cited by 12 publications

References 20 publications

Nanomechanical probing of the layer/substrate interface of an exfoliated InSe sheet on sapphire

Nanomechanical probing of the layer/substrate interface of an exfoliated InSe sheet on sapphire

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

Imaging of a patterned and buried molecular layer by coherent acoustic phonon spectroscopy

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