scholarly journals An Experimental and Theoretical Study of Impact of Device Parameters on Performance of AlN/Sapphire-Based SAW Temperature Sensors

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 40
Author(s):  
Hongrui Lv ◽  
Yinglong Huang ◽  
Yujie Ai ◽  
Zhe Liu ◽  
Defeng Lin ◽  
...  
Keyword(s):  
Electromechanical Coupling ◽  
Model Simulation ◽  
Acoustic Propagation ◽  
Elastic Stiffness ◽  
Temperature Sensors ◽  
Propagation Direction ◽  
Electromechanical Coupling Coefficient ◽  
Aln Film ◽  
Quality Factor Q ◽  
The Impact

The impact of device parameters, including AlN film thickness (hAlN), number of interdigital transducers (NIDT), and acoustic propagation direction, on the performance of c-plane AlN/sapphire-based SAW temperature sensors with an acoustic wavelength (λ) of 8 μm, was investigated. The results showed that resonant frequency (fr) decreased linearly, the quality factor (Q) decreased and the electromechanical coupling coefficient (Kt2) increased for all the sensors with temperature increasing from −50 to 250 °C. The temperature coefficients of frequency (TCFs) of sensors on AlN films with thicknesses of 0.8 and 1.2 μm were −65.57 and −62.49 ppm/°C, respectively, indicating that a reduction in hAlN/λ favored the improvement of TCF. The acoustic propagation direction and NIDT did not obviously impact the TCF of sensors, but they significantly influenced the Q and Kt2 of the sensors. At all temperatures measured, sensors along the a-direction exhibited higher fr, Q and Kt2 than those along the m-direction, and sensors with NIDT of 300 showed higher Q and Kt2 values than those with NIDT of 100 and 180. Moreover, the elastic stiffness of AlN was extracted by fitting coupling of modes (COM) model simulation to the experimental results of sensors along different directions considering Euler transformation of material parameter-tensors. The higher fr of the sensor along the a-direction than that along the m-direction can be attributed to its larger elastic stiffness c11, c22, c44, and c55 values.

LEAKY SURFACE ACOUSTIC WAVES IN SINGLE-CRYSTAL AlN SUBSTRATE

2004 ◽  
Vol 14 (03) ◽  
pp. 837-846 ◽  
Author(s):  
GANG BU ◽  
DAUMANTAS CIPLYS ◽  
MICHAEL S. SHUR ◽  
LEO J. SCHOWALTER ◽  
SANDRA B. SCHUJMAN ◽  
...  
Keyword(s):  
Single Crystal ◽  
Acoustic Waves ◽  
Electromechanical Coupling ◽  
Surface Acoustic Waves ◽  
Propagation Direction ◽  
Electromechanical Coupling Coefficient ◽  
Coupling Coefficients ◽  
Leaky Waves ◽  
Temperature Coefficient Of Frequency ◽  
Piezoelectric Constants

We report on the velocity V and the electromechanical coupling coefficient K2 of the first and the second leaky surface acoustic waves in various propagation directions in the a-plane AlN single-crystal. For c-propagation direction, the second leaky wave exhibited the velocity of 11016 m/s and K2 of 0.45%. For this direction, the temperature coefficient of frequency was found to be -30 ppm/°C. A near match of the velocities of the plane and leaky waves in the a-plane AlN allowed us to establish analytical relationships between the piezoelectric and elastic constants. A full set of elastic and piezoelectric constants of AlN has been evaluated by fitting the measured and calculated dependencies of velocities and electromechanical coupling coefficients on the propagation direction for both Rayleigh and leaky waves.

scholarly journals Surface acoustic wave temperature properties in alpha-GeO2 crystal

2021 ◽  
Vol 2131 (5) ◽  
pp. 052098
Author(s):  
R M Taziev
Keyword(s):  
Wave Propagation ◽  
Surface Wave ◽  
Acoustic Wave ◽  
Temperature Coefficient ◽  
Surface Acoustic Wave ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Propagation Direction ◽  
Electromechanical Coupling Coefficient ◽  
Wave Propagation Direction

Abstract In this study, the surface acoustic wave (SAW) temperature properties in flux-grown α-GeO2 crystal are numerically investigated. It is shown that the SAW velocity temperature change substantially depends only on the temperature coefficient of three elastic constants: C66, C44 and C14 for crystal cuts and wave propagation directions, where SAW has high electromechanical coupling coefficient. The SAW temperature coefficient of delay (TCD) for these crystal cuts are in the range from -40 ppm /°C to -70 ppm /°C. In contrast to alpha-quartz, the surface wave TCD values are not equal to zero in Z-, Y- , and Z- rotated cuts of α-GeO2 single crystal. Its values are comparable in the magnitude with the surface wave TCD values in lithium tantalate. In the crystal grown from the melt, the interdigital transducer (IDT) conductance has two times larger amplitude than that in hydrothermally grown a-GeO2. The leaky acoustic wave excited by IDT on Z+120°-cut and wave propagation direction along the X-axis, has an electromechanical coupling coefficient 5 times less than that for surface wave.

SURFACE-ACOUSTIC-WAVE FIELD AND ACOUSTO-OPTIC INTERACTION IN AlN/128-DEG-ROTATED Y-CUT X-PROPAGATION LiNbO3

2013 ◽  
Vol 27 (05) ◽  
pp. 1350032
Author(s):  
JUNTAO WANG ◽  
QUN HAN ◽  
JIPING NING ◽  
YANG HE
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Diffraction Efficiency ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Guided Wave ◽  
Electromechanical Coupling Coefficient ◽  
Overlap Integral ◽  
Aln Film ◽  
First Time

The efficiency of guided-wave acousto-optic (AO) interaction in AlN /128-deg-rotated Y-cut X-propagation lithium niobate (128-deg YX- LiNbO 3) structure is analyzed theoretically for the first time by determining the overlap integral between the optical and the surface acoustic wave (SAW) field distribution. The results show that the use of an AlN film can increase the phase velocity of SAW, the electromechanical coupling coefficient and the diffraction efficiency of AO interaction. A maximum of 9.33% for the electromechanical coupling coefficient is obtained when the normalized thickness of AlN film equals 0.09. The diffraction efficiency has a significant improvement when the normalized thickness of AlN film is increased from 0 to 0.05. And, the improvement for the TM polarization is more evident than that for the TE polarization. However, for a well-concentrated optical waveguide, the use of an AlN film reduces the diffraction efficiency of the TM polarization when the SAW frequency is low.

Efficiency Characterization of Piezoelectrics for Power

2004 ◽  
Author(s):  
J. H. Cho ◽  
J. C. Raupp ◽  
P. D. Hayenga ◽  
R. F. Richards ◽  
D. F. Bahr ◽  
...  
Keyword(s):  
Energy Conversion ◽  
Quality Factor ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Electromechanical Coupling Coefficient ◽  
Piezoelectric Cantilever ◽  
Quality Factor Q ◽  
Piezoelectric Devices

The efficiency of energy conversion by piezoelectric devices depends upon the quality factor Q, and electromechanical coupling coefficient k2. Efficiency, Q, and k2 were measured for a piezoelectric cantilever and piezoelectric stack, and compared to a model of the efficiency in terms of Q and k2. The model and experiment agree very well.

Integration of PZT on SOI Wafers: Increasing Piezoelectric Film Thickness for Providing a Wide Range of Ultrasonic MEMS Applications

2006 ◽  
Vol 969 ◽  
Author(s):  
Brahim Belgacem ◽  
Florian Calame ◽  
Paul Muralt
Keyword(s):  
Electromechanical Coupling ◽  
Piezoelectric Coefficient ◽  
Sol Gel ◽  
Equivalent Circuit Model ◽  
Ultrasonic Transducers ◽  
Electromechanical Coupling Coefficient ◽  
Wide Range ◽  
Pzt Films ◽  
Gel Technique ◽  
Quality Factor Q

AbstractPiezoelectric micromachined ultrasonic transducers comprising a 10 μm thick Si device layer and a 1-4 μm thick piezoelectric PZT layer were investigated. The PZT films were deposited by a sol-gel technique. The transverse piezoelectric coefficient was measured as -14.9 C/m2. The electromechanical coupling increased with PZT thickness, as expected. The influence of both the shape and area of the top electrode on the device performance has been investigated. The electromechanical coupling coefficient (k) and quality factor (Q) have been measured in air and were fitted to an equivalent circuit model. The maximal k2 was obtained as 7.8%.

The Acoustic Impedance and other Properties of (1-3) Piezoceramics Polymer Composite

2018 ◽  
Vol 879 ◽  
pp. 51-56
Author(s):  
Tawee Tunkasiri ◽  
Jerapong Tontrakoon ◽  
Gobwute Rujijanagul ◽  
Uraiwan Intatha ◽  
Kamonpan Pengpat ◽  
...  
Keyword(s):  
Polymer Composites ◽  
Acoustic Impedance ◽  
Electromechanical Coupling ◽  
Sintering Temperature ◽  
Mechanical Quality Factor ◽  
Electromechanical Coupling Coefficient ◽  
Mechanical Quality ◽  
Lower Volume ◽  
Quality Factor Q ◽  
Fast Firing

The work is focused on an attempt to develop a route for the fabrication of piezoceamic-polymer composites having (1-3) type connectivity. The process included the extrusion of rods of diameter approximately 200 mm. A commercial piezoelectric, PC-5 was modified by addition of a lithium/bismuth based glass former together with excess PbO to lower the sintering temperature to about 1000 °C. The fast firing sintering was employed. The rods were assembled and impregnated with an epoxy resin to form 1-3 composites containing approximately 50 and 20 vol% piezoceramic. The measurement values showed that, the piezoelectric constant, d33= 232 pCN-1and 215 pCN-1, thickness electromechanical coupling coefficient, kt= 0.51 and 0.5 and the mechanical quality factor, Qm= 14 and 5 for the composites containg PZT rods at 50 vol% and 20 vol% respectively. Their acoustic impedances were 5.1 and 3.6 for the 50 vol% and 20 vol% of PZT rods respectively. The results show that with lower volume% of PZT could result in lower acoustic impedance which can be further improved for biomedical imaging and hydrophone applications.

scholarly journals Fabrication of a 3.5-GHz Solidly Mounted Resonator by Using an AlScN Piezoelectric Thin Film

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1151
Author(s):  
Chan-Yu Chung ◽  
Ying-Chung Chen ◽  
Yu-Cheng Chen ◽  
Kuo-Sheng Kao ◽  
Yu-Chen Chang
Keyword(s):  
Thin Film ◽  
Resonance Frequency ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Bragg Reflector ◽  
Electromechanical Coupling Coefficient ◽  
Axis Orientation ◽  
X Ray ◽  
Aln Film ◽  
Piezoelectric Thin Film

In this study, a 3.5-GHz solidly mounted resonator (SMR) was developed by doping scandium in aluminum nitride to form AlScN as the piezoelectric thin film. Molybdenum (Mo) of 449 nm thickness and silicon dioxide (SiO2) of 371 nm thickness were used as the high and low acoustic impedance films, respectively, which were alternately stacked on a silicon substrate to form a Bragg reflector. Then, an alloy target with atomic ratio of 15% Sc was adopted to deposit the piezoelectric AlScN thin film on the Bragg reflector, using a radio frequency magnetron sputtering system. The characteristics of the c-axis orientation of the AlScN thin films were optimized by adjusting sputtering parameters as sputtering power of 250 W, sputtering pressure of 20 mTorr, nitrogen gas ratio of 20%, and substrate temperature of 300 °C. Finally, a metal top electrode was coated to form a resonator. The X-ray diffraction (XRD) analysis showed that the diffraction peak angles of the AlScN film shifted towards lower angles in each crystal phase, compared to those of AlN film. The energy dispersive X-ray spectrometer (EDX) analysis showed that the percentage of scandium atom in the film is about 4.5%, regardless of the sputtering conditions. The fabricated resonator exhibited a resonance frequency of 3.46 GHz, which was a small deviation from the preset resonance frequency of 3.5 GHz. The insertion loss of −10.92 dB and the electromechanical coupling coefficient of 2.24% were obtained. As compared to the AlN-based device, the AlScN-based resonator exhibited an improved electromechanical coupling coefficient by about two times.

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