LOW NOISE PIEZOELECTRIC SENSORS

1 . A device, comprising:

a first conductive layer;

a second conductive layer; and

a piezoelectric layer between the first conductive layer and the second conductive layer, the piezoelectric layer comprising a dissipation factor of less than about 0.1%.

2 . The device of claim 1 , wherein the piezoelectric layer comprises aluminum scandium nitride having a scandium content of greater than 15%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride.

3 . The device of claim 1 , wherein the piezoelectric layer comprises aluminum scandium nitride having a scandium content of greater than 30%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride.

4 . The device of claim 1 , wherein the piezoelectric layer comprises a d 31 coupling coefficient having an absolute value greater than about 3.68 pC/N.

5 . The device of claim 1 , wherein at least one of the first conductive layer or the second conductive layer comprises a metal layer having a thickness of less than 100 nm.

6 . The device of claim 1 , wherein the piezoelectric layer comprises a first piezoelectric layer, the device further comprising:

a third conductive layer; and

a second piezoelectric layer between the second conductive layer and the third conductive layer, the second piezoelectric layer having a dissipation factor of less than about 0.1%.

7 . The device of claim 1 , wherein the device comprises a microphone, an accelerometer, a pressure sensor, a speaker, an ultrasound transmitter, or an ultrasound receiver.

8 . The device of claim 1 , wherein the device comprises a cantilever.

9 . The device of claim 1 , wherein the first conductive layer is deposited on an adhesive layer.

10 . The device of claim 9 , where the adhesive layer comprises titanium, aluminum scandium nitride, aluminum nitride, or chromium.

11 . A device, comprising:

a first conductive layer;

a second conductive layer; and

a piezoelectric layer between the first conductive layer and the second conductive layer, the piezoelectric layer comprising aluminum scandium nitride having a scandium content of greater than 15%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride.

12 . The device of claim 11 , wherein the piezoelectric layer comprises aluminum scandium nitride having a scandium content of greater than 30%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride.

13 . The device of claim 11 , wherein the piezoelectric layer comprises a dissipation factor of less than about 0.1%.

14 . The device of claim 11 , wherein the piezoelectric layer comprises a d 31 coupling coefficient having an absolute value greater than about 3.68 pC/N.

15 . The device of claim 11 , wherein at least one of the first conductive layer or the second conductive layer comprises a metal layer having a thickness of less than 100 nm.

16 . The device of claim 11 , wherein the piezoelectric layer comprises a first piezoelectric layer, the device further comprising:

a third conductive layer; and

a second piezoelectric layer between the second conductive layer and the third conductive layer, the second piezoelectric layer having a dissipation factor of less than about 0.1%.

17 . The device of claim 11 , wherein the device comprises a microphone, an accelerometer, a pressure sensor, a speaker, an ultrasound transmitter, or an ultrasound receiver.

18 . The device of claim 11 , wherein the device comprises a cantilever.

19 . The device of claim 18 , wherein the first conductive layer is deposited on an adhesive layer.

20 . The device of claim 19 , where the adhesive layer comprises titanium, aluminum scandium nitride, aluminum nitride, or chromium.

21 . A method of fabricating a device, comprising:

depositing a first conductive layer on a substrate;

depositing a piezoelectric layer on the first conductive layer, the piezoelectric layer comprising aluminum scandium nitride having a scandium content of greater than 15%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride; and

depositing a second conductive layer on the piezoelectric layer.

22 . The method of claim 21 , wherein the substrate comprises a silicon wafer having at least a 200 mm diameter.

23 . The method of claim 21 , wherein the piezoelectric layer is deposited by pulsed laser deposition.

24 . The method of claim 21 , wherein the piezoelectric layer comprises at least one of a dissipation factor of less than about 0.1% or a d 31 coupling coefficient having an absolute value greater than about 3.68 pC/N.

25 . The method of claim 21 , wherein the piezoelectric layer comprises aluminum scandium nitride having a scandium content of greater than 30%, wherein the scandium content and an aluminum content comprises 100% of the aluminum scandium nitride.

26 . The method of claim 21 , further comprising:

depositing an oxide layer on the substrate;

depositing an adhesive layer on the oxide layer, the adhesive layer comprising titanium, aluminum scandium nitride, aluminum nitride, or chromium; and

depositing the first conductive layer on the adhesive layer.

27 . The method of claim 21 , further comprising:

before depositing the piezoelectric layer, processing the first conductive layer to form at least one gap in the first conductive layer.

28 . The method of claim 21 , further comprising:

processing the deposited material to produce one or more structures that form a piezoelectric sensor.

29 . The method of claim 28 , wherein at least one of the one or more structures comprises a cantilever.

30 . The method of claim 28 , wherein the piezoelectric sensor comprises a microphone, an accelerometer, a pressure sensor, a speaker, an ultrasound transmitter, or an ultrasound receiver.