Elastic wave device with sub-wavelength thick piezoelectric layer and high velocity layer
Aspects of this disclosure relate to an elastic wave device. The elastic wave device includes a sub-wavelength thick piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and a high velocity layer configured to inhibit an elastic wave from leaking from the piezoelectric layer at anti-resonance.
1. An elastic wave device comprising:
a piezoelectric layer having a cut angle in a cut angle range from −10° to 60°;
an interdigital transducer electrode on the piezoelectric layer, the interdigital transducer electrode configured to generate an elastic wave having a wavelength of λ, the interdigital transducer electrode having a thickness in a first thickness range from 0.02λ to 0.1λ, and the piezoelectric layer having a thickness that is less than λ; and
a high velocity layer having a higher bulk velocity than a velocity of the elastic wave and being configured to inhibit the elastic wave from leaking from the piezoelectric layer at anti-resonance.
2. The elastic wave device of claim 1 further comprising a temperature compensating layer disposed between the high velocity layer and the piezoelectric layer.
3. The elastic wave device of claim 1 wherein the high velocity layer is a silicon layer.
4. The elastic wave device of claim 1 wherein the piezoelectric layer includes a lithium niobate layer.
5. The elastic wave device of claim 1 wherein the piezoelectric layer includes a lithium tantalate layer.
6. The elastic wave device of claim 1 wherein the thickness of the interdigital transducer electrode is between 0.05λ and 0.1λ.
7. The elastic wave device of claim 1 wherein the cut angle is in a range from 15° to 35°.
8. The elastic wave device of claim 1 wherein the thickness of the piezoelectric layer is in a second thickness range from 0.35λ to 0.8λ.
9. The elastic wave device of claim 1 wherein the interdigital transducer electrode includes aluminum.
10. The elastic wave device of claim 1 wherein the high velocity layer is bonded to and in physical contact with the piezoelectric layer.
11. An elastic wave device comprising:
a lithium niobate layer having a cut angle in a cut angle range from −10° to 60°;
an interdigital transducer electrode on the lithium niobate layer, the interdigital transducer electrode configured to generate an elastic wave having a wavelength of λ, and the lithium niobate layer having a thickness in a thickness range from 0.35λ to 0.8λ
a high velocity layer having a higher bulk velocity than a velocity of the elastic wave, the high velocity layer configured to inhibit the elastic wave from leaking from the lithium niobate layer at anti-resonance; and
a temperature compensating layer disposed between the high velocity layer and the lithium niobate layer, the temperature compensating layer having a positive temperature coefficient of frequency, the elastic wave device being arranged so as to have an electromechanical coupling coefficient of at least 26%.
12. The elastic wave device of claim 11 wherein the temperature compensating layer is a silicon dioxide layer.
13. The elastic wave device of claim 11 wherein the temperature compensating layer has a thickness of less than 0.5λ.
14. The elastic wave device of claim 11 wherein the cut angle is in a range from −10° to 30°.
15. An elastic wave device comprising:
a lithium tantalate layer having a cut angle in a cut angle range from −10° to 50°;
an interdigital transducer electrode on the lithium tantalate layer, the interdigital transducer electrode configured to generate an elastic wave having a wavelength of λ, and the lithium tantalate layer having a thickness that is less than λ;
a high velocity layer having a higher bulk velocity than a velocity of the elastic wave, the high velocity layer configured to inhibit the elastic wave from leaking from the lithium tantalate layer at anti-resonance; and
a temperature compensating layer disposed between the high velocity layer and the lithium tantalate layer, the temperature compensating layer having a positive temperature coefficient of frequency.
16. The elastic wave device of claim 15 wherein the temperature compensating layer is a silicon dioxide layer.
17. The elastic wave device of claim 15 wherein the temperature compensating layer has a thickness of less than 0.5λ.
18. The elastic wave device of claim 15 wherein the interdigital transducer electrode has a thickness in a second thickness range from 0.02λ to 0.1λ.
19. The elastic wave device of claim 15 wherein the cut angle is in a range from −10° to 30°.
20. The elastic wave device of claim 15 wherein the thickness of the lithium tantalate layer is in a thickness range from 0.25λ to 0.8λ.