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A novel type of hybrid resonator based on BAW transformation into SAW in a ridged layered structure was fabricated and characterized. Bulk waves are excited by micromachined piezoelectric AlScN pillars located on the non-piezoelectric Si and sapphire substrates. The effect of film thickness and etching depth on the electromechanical coupling and velocity dispersion were calculated by finite element...
For more accurate and rapid measurements of Brillouin light scattering, a technique with artificially induced acoustic phonons was proposed using a ScAlN film. The ScAlN film has a giant electromechanical coupling coefficient and can radiate coherent phonons in the sub GHz and GHz range. Making use of the induced phonons, we observed Brillouin scattering in the silica bulk sample. For efficient radiation...
ScAlN films is attractive for high-frequency piezoelectric devices. In previous study, we demonstrated Sc ingot sputtering in which Sc ingots were set on an Al metal target. Oxidization of Sc ingots was seriously problem because the c-axis orientation of ScAlN films was degraded. In this study, we investigated the energy distributions of O− negative ion which enter the substrate during the deposition...
Ultrasonic transducers made by sol-gel composite materials have been developed for high temperature continuous monitoring applications. PbTiO3 (PT)/ Pb(Zr,Ti)O3 (PZT) sol-gel composite ultrasonic transducers have high temperature durability and high sensitivity from room temperature (RT) to 300 °C. However, poling of PT/PZT is difficult because of high coercive field of PT and high temperature poling...
The high cost of conventional surface acoustic wave (SAW) devices limits its widespread use as micro-sensor and actuator for lab-on-a-chip applications. Solution-processed, inexpensive SAW device based on poly[(vinylidenefluoride-co-trifluoroethylene] [P(VDF-TrFE)], a ferroelectric polymer, is an alternative route to address this issue. However, incompatibility of P(VDF-TrFE) films with photoresist...
In this paper, we present piezoelectric co-doped (Mg,Hf)xAl1−xN thin films, where the dopant concentration x is in the range of 0–0.13. The (Mg,Hf)xAl1−xN thin films were prepared on Si (100) substrates with a dual magnetron with AC power applied between two ring targets. The compositions of the targets were pure Al and Al-Mg-Hf metals. The composition of the films was controlled by adjusting a DC...
This paper investigates the possibility of using ferroelectret films to produce wideband ultrasonic transducers for applications in water immersion and medical imaging. Ultrasonic transducers with different sizes (apertures) were fabricated using a polypropylene ferroelectret film (0.6 MHz thickness resonant frequency) as active component. Then, they were characterized in pulse-echo operation mode...
The experimental studies of temperature coefficient of frequency (TCF) of SAW resonators were usually modeled by TCF models first proposed by Bechmann, Ballato and Lukaszeck[1]. These models unfortunately were not frame invariant with regards to the material property tensors of the crystal substrate and metal interdigital transducers (IDTs). Furthermore the models did not have the 3rd order nonlinear...
We investigate the potential utility of Magneto-hydrodynamics to enhance the acoustic pressure of electrically induced plasma sparks. We compared the displacements of a mylar polyester film caused by plasma sparks in three different settings: Case 1: No magnetic field; Case 2: Magnetic field generating Lorentz force towards the film, and Case 3: Magnetic field generating Lorentz in direction away...
Our work deals with the study of the dynamic characteristics of a single circular CMUT transducer under squeeze film damping effect. A simplified analytical approach is developed for parallel plate approximation for the electromechanical behavior and the squeeze film damping. Analytically calculated results demonstrates, that trends of resonant frequency with bias voltage are defined by the ratio...
We propose a new approach called localized photothermal curing (LPC) to fabricate carbon nanotube (CNT)-polydimethylsiloxane (PDMS) composite transmitters for optoacoustic generation of high-frequency, high-amplitude ultrasound. The LPC uses nanosecond-pulsed laser irradiation to cure prepolymer liquid surrounding CNT strands in a composite form. These transmitters can produce peak pressure amplitudes...
This paper is aimed at examining the validity of material constants reported for the use in surface acoustic wave (SAW) device simulations. At first, based on the full set of material constants calculated by the first principle, bulk acoustic wave (BAW) velocities are calculated for ScxAl1−xN and compared with published experimental results. Then, the effects of ScxAl1−xN material constants with different...
In this paper, we investigate influence of the electrode on the third-order nonlinearity of SAW devices. First, some one-port resonators are fabricated on 42°YX-LiTaO3 substrates with different electrode material or electrode crystallinity, and their nonlinear signal levels are estimated. As the result, nonlinear signal levels change markedly with electrode material and crystallinity of electrode...
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