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.

scholarly journals Analysis of surface acoustic wave properties in CaYAl3O7 single crystal

2021 ◽  
Vol 2131 (5) ◽  
pp. 052099
Author(s):  
R M Taziev
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Single Crystal ◽  
Surface Acoustic Wave ◽  
Coupling Coefficient ◽  
Propagation Direction ◽  
Tetragonal Symmetry ◽  
Flow Angle ◽  
Wave Propagation Direction ◽  
Wave Properties

Abstract The success on the growth of new piezoelectric materials allows sufficiently increase the operating temperature of the surface acoustic wave (SAW) devices from 300°C to 1000°C. A new calcium yttrium aluminate (CaYAl3O7) single crystal of the tetragonal symmetry has piezoelectric properties up to the temperature of 1000°C. The paper presents a numerical study of the surface acoustic wave properties in the crystal. The SAW velocity, electromechanical coupling coefficient and power flow angle are studied for different crystal cuts of CaYAl3O7. It is shown that the maximum value of SAW coupling coefficient (0.24%) is on the Z+60°-cut and wave propagation direction along the X-axis of the crystal. For the Z-cut and wave propagation direction along the X+45°-axis of crystal, the SAW coupling coefficient is equal to 0.2%. These two cuts of the crystal are potentially useful for SAW device applications.

scholarly journals Enhanced Properties of SAW Device Based on Beryllium Oxide Thin Films

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 332
Author(s):  
Namrata Dewan Soni ◽  
Jyoti Bhola
Keyword(s):  
Acoustic Wave ◽  
Phase Velocity ◽  
Temperature Coefficient ◽  
Surface Acoustic Wave ◽  
Layered Structure ◽  
Coupling Coefficient ◽  
Electromechanical Coupling ◽  
Beryllium Oxide ◽  
Negative Temperature ◽  
Electromechanical Coupling Coefficient

The present study depicts the first-ever optimized surface acoustic wave (SAW) device based on Beryllium Oxide (BeO) thin film. The feasibility of surface acoustic wave devices based on BeO/128° YX LiNbO3 layered structure has been examined theoretically. The SAW phase velocity, electromechanical coupling coefficient, and temperature coefficient of delay for BeO/128° YX LiNbO3 layered structure are calculated. The layered structure is found to exhibit optimum value of phase velocity (4476 ms−1) and coupling coefficient (~9.66%) at BeO over layer thickness of 0.08λ. The BeO (0.08λ)/128° YX LiNbO3 SAW device is made temperature stable, by integrating it with negative temperature coefficient of delay (TCD) TeO3 over layer of thickness 0.026λ.

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.

Properties of Surface Acoustic Waves in AlN And GaN

2002 ◽  
Vol 743 ◽  
Author(s):  
Jianyu Deng ◽  
Daumantas Ciplys ◽  
Gang Bu ◽  
Michael Shur ◽  
Remis Gaska
Keyword(s):  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
Coupling Coefficient ◽  
Acoustic Waves ◽  
Electromechanical Coupling ◽  
Surface Acoustic Waves ◽  
Elastic Displacement ◽  
Electromechanical Coupling Coefficient ◽  
Coupling Coefficients ◽  
Calculation Results

ABSTRACTThe surface acoustic wave velocities, electromechanical coupling coefficients, and the spatial distributions of both elastic displacement and electric potential have been calculated for various configurations of gallium nitride and aluminum nitride. The electromechanical coupling coefficient values of 0.13 % in GaN and 0.29 % in AlN have been predicted. The maximum electromechanical coupling coefficient values of 0.24 % at Euler angles (0, 54°, 90°) in GaN and 1.08 % at (0, 53°, 90°) in AlN have been found. For GaN layer-on- sapphire substrate structures, the SAW velocity and electromechanical coupling coefficient have been calculated as functions of layer thickness and acoustic wavelength. The experimentally measured values of the surface acoustic wave velocity and electromechanical coupling coefficient are in satisfactory agreement with the calculation results.

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