Imaging of acoustic fields in bulk acoustic-wave thin-film resonators

Safar, H.; Kleiman, R. N.; Barber, Bradley P.; Gammel, P. L.; Pastalan, J.; Huggins, H. A.; Fetter, Linus A.; Miller, Ronald Mellado

doi:10.1063/1.126901

Cited by 22 publications

(13 citation statements)

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“…One example is the use of atomic force microscopy (AFM) to characterize surface vibrations [44][45][46][47]. It cannot be considered as a truly non-contact method, as it can significantly influence the sample under study [48], although techniques have been developed to minimize the effect [49].…”

Section: Optical Characterization Of Surface Vibrationsmentioning

confidence: 99%

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Kokkonen

Meltaus

Pensala

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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Aalto University publication series DOCTORAL DISSERTATIONS 112/2014 © Kimmo Kokkonen AbstractThe research summarized in this dissertation focuses on the development of a heterodyne scanning laser interferometer and of data-analysis techniques for the characterization and analysis of the surface vibration fields in microacoustic devices and test structures.The heterodyne laser interferometer enables a phase-sensitive, absolute-amplitude detection of the out-of-plane component of a surface vibration field, with a minimum detectable amplitude of less than a picometer, while the lateral resolution is better than 1 micrometer. The instrument features a flat frequency response up to 6 GHz.The phase-sensitive absolute-amplitude data enables the visualization of the actual wave behavior in electromechanical components and test structures, but more importantly, it is the basis for further analysis. The research instrument is applied to the study of electroacoustic devices based on surface acoustic wave (SAW) and bulk acoustic wave (BAW) technologies. Two novel SAW devices are studied in detail: a phononic crystal (PnC) structure and a scattering structure resulting in a random wave field. PnCs are acoustic metamaterials that can provide engineered material properties. The laser interferometric measurements were amongst the first to directly characterize the wave interaction with the PnC. SAW slowness curves of an anisotropic substrate material are extracted by measuring and analyzing the scattered random wave field. Data analysis methods are developed further in the context of BAW research by experimentally addressing two important aspects of device design: the correct operation of the acoustic reflector used to confine the energy in the resonator, and investigation of the role of the dispersion and standing wave resonances to the spurious responses often observed in high-Q resonators. Fourier transform techniques are used for selective visualization of wave fields and for the extraction of the dispersion characteristics of the plate-waves. The dispersion data are then further used to analyze the transfer characteristics of an acoustic reflector and to study the properties of lateral eigenresonances and the lateral energy confinement in detail.The research described in this thesis provides a detailed characterization of the operation of SAW and BAW devices and effects within, highlighting and further developing the experimental characterization capabilities and data-analysis methods.Keywords laser interferometry, microacoustics, surface acoustic waves, bulk acoustic waves Tiivistelmä Väitöskirjatyö käsittelee heterodyne-tyyppisen laserinterferometrin sekä interferometrin tuottaman datan analyysitekniikoiden kehittämistä pintavärähtelykenttien karakterisoimiseksi ja analysoimiseksi mikroakustisissa komponenteissa ja testirakenteissa.Työssä rakennettu heterodynelaserinterferometri mahdollistaa pintavärähtelyiden vaiheherkät absoluuttiamplitudimittaukset aina 6 GHz taajuuteen asti. Laitteisto kykenee värähtely-kenttien k...

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Section: Optical Characterization Of Surface Vibrationsmentioning

confidence: 99%

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Kokkonen

Meltaus

Pensala

et al. 2012

IEEE Trans. Ultrason., Ferroelect., Freq. Contr.

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“…The amplitude of the vibration is then measured by using the modulation signal as the reference for the lock-in amplification of the microscope's cantilever deflection signal. The capability of this technique to measure the rf frequency response and to image acoustic wave fields in solidly mounted resonators has been previously demonstrated by Safar et al 9 In that work, f mod was kept constant at a value in the 2 -20 kHz range. In fact, beside the upper limit for f bandwidth ͑typically 1 -10 KHz͒ also establishes a lower limit for f mod .…”

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confidence: 99%

“…Image ͑a͒ shows the rf vibration pattern that results from the excitation of high order Lamb wave modes at frequencies above the main thickness mode, as reported in other studies. 6,9,10 This standing-wave pattern consists of a short wave-length structure with 2 -5 m features aligned parallel to the sides of the membrane. Remarkably, the vibration amplitude image suffers an important change when f mod is reduced, as shown in image ͑b͒.…”

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confidence: 99%

“…As an alternative, scanning acoustic force microscopy ͑SAFM͒ provides a comparable vibration amplitude resolution with a nanometerscale lateral resolution. 8,9 Specifically developing SAFM to study mechanical resonators takes advantage of its superior lateral resolution and experimental versatility, and it can also provide methods to obtain further information about the physical properties and performance of these devices.…”

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confidence: 99%

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Scanning acoustic force microscopy characterization of thermal expansion effects on the electromechanical properties of film bulk acoustic resonators

Paulo

Liu

Bokor

2005

Applied Physics Letters

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This letter demonstrates the application of scanning acoustic force microscopy for the characterization of film bulk acoustic resonators beyond detection of the gigahertz vibration amplitude and acoustic wave field imaging. We present a method to measure thermal expansion effects on these resonators by modulating the driving signal amplitude and then varying the modulation frequency from a few hertz to several tens of kilohertz. For the particular device considered here, we show the influence of thermal expansion effects on its electromechanical response and the acoustic wave field images. The thermal relaxation time constant of the resonator is measured and compared with a theoretical estimation based on the heat transfer analysis of the system.

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“…An AFM cantilever is brought in close proximity of the resonator to probe its oscillations. Several groups have used contact interactions [11][12][13]; tapping mode AFM has also been employed for less intrusive probing [14][15][16]. In addition, other AFMbased approaches, including acoustic force microscopy [17] and electrostatic scanning probe microscopy [18], have also been applied to measuring small oscillations.…”

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confidence: 99%

Dynamic interactions between oscillating cantilevers: Nanomechanical modulation using surface forces

Basarir

Ekinci

2013

Applied Physics Letters

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Dynamic interactions between two oscillating micromechanical cantilevers are studied. In the experiment, the tip of a high-frequency cantilever is positioned near the surface of a second lowfrequency cantilever. Due to the highly nonlinear interaction forces between the two surfaces, thermal oscillations of the low-frequency cantilever modulate the driven oscillations of the highfrequency cantilever. The dissipations and the frequencies of the two cantilevers are shown to be coupled, and a simple model for the interactions is presented. The interactions studied here may be useful for the design of future micro and nanoelectromechanical systems for mechanical signal processing; they may also help realize coupled mechanical modes for experiments in non-linear dynamics. [6,7]. Miniaturized mechanical devicesHere, we study dynamic interactions between two oscillating micromechanical cantilevers and harvest these interactions for mechanical signal modulation and detection. In the experiment, the carrier signal from a high-frequency microcantilever oscillator is modulated by low-frequency thermal oscillations of a second microcantilever by simply bringing the two microcantilevers close together. The approach relies upon the strong inherent nonlinearity of the interaction force between two surfaces in close proximity and offers several advantages. The modulation is purely mechanical, and mechanical signals need not be converted to electrical signals. The strength of the coupling between the two mechanical signals, and hence the modulation index, can be adjusted by changing the distance between the two microcantilevers. Conservative and dissipative components of the interaction enable tuning of the frequencies and dissipation. Conversely, monitoring the modulation on the carrier signal allows for sensitive mechanical displacement detection. Because the approach offers prospects for creating coupled mechanical modes [10] with tunable coupling, it may be useful in fundamental investigations in nonlinear dynamics.Our approach is derived from dynamic mode atomic force microscopy (AFM). Related to our work here, various AFM modalities have been used to detect the motion of micro-and nano-mechanical resonators. In these

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Imaging of acoustic fields in bulk acoustic-wave thin-film resonators

Cited by 22 publications

References 5 publications

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Measurement of evanescent wave properties of a bulk acoustic wave resonator [Letters]

Scanning acoustic force microscopy characterization of thermal expansion effects on the electromechanical properties of film bulk acoustic resonators

Dynamic interactions between oscillating cantilevers: Nanomechanical modulation using surface forces

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