Structures for piezoelectric actuator to increase displacement and maintain stiffness
A piezoelectric actuator including an anchor, an elastic layer having a first end coupled to the anchor, and a piezoelectric layer on the elastic layer. The elastic layer includes a solid sublayer including an elastic material and a second sublayer including a plurality of cavities. The piezoelectric layer is on the second sublayer of the elastic layer and includes a top electrode, a bottom electrode, and a piezoelectric material layer between the top electrode and the bottom electrode.
1. A micro-mirror assembly comprising:
a substrate;
a first piezoelectric actuator coupled to the substrate;
a second piezoelectric actuator coupled to the substrate; and
a micro-mirror positioned between the first piezoelectric actuator and the second piezoelectric actuator, the micro-mirror including:
a first edge coupled to the first piezoelectric actuator; and
a second edge opposing the first edge and coupled to the second piezoelectric actuator,
wherein each of the first piezoelectric actuator and the second piezoelectric actuator comprises:
an elastic layer comprising:
a solid sublayer including an elastic material; and
a second sublayer including a plurality of cavities; and
a piezoelectric layer on the second sublayer of the elastic layer,
wherein each of the plurality of cavities is characterized by a height greater than a threshold value or greater than a half of a thickness of the solid sublayer of the elastic layer.
2. The micro-mirror assembly of claim 1 , wherein the plurality of cavities includes a one-dimensional array or a two-dimensional array of cavities.
3. The micro-mirror assembly of claim 1 , wherein the piezoelectric layer comprises:
a top electrode;
a bottom electrode; and
a piezoelectric material layer between the top electrode and the bottom electrode.
4. The micro-mirror assembly of claim 1 , wherein the piezoelectric layer is in physical contact with the second sublayer of the elastic layer.
5. The micro-mirror assembly of claim 1 , wherein:
the elastic layer further comprises a top sublayer on the second sublayer; and
the piezoelectric layer is in physical contact with the top sublayer of the elastic layer.
6. The micro-mirror assembly of claim 1 , wherein:
the elastic layer further comprises a third sublayer including a second plurality of cavities;
the solid sublayer is between the second sublayer and the third sublayer; and
each of the first piezoelectric actuator and the second piezoelectric actuator further comprises a second piezoelectric layer coupled to the third sublayer of the elastic layer.
7. The micro-mirror assembly of claim 1 , wherein the micro-mirror includes a gimbal structure.
8. The micro-mirror assembly of claim 1 , wherein the first edge of the micro-mirror is coupled to the first piezoelectric actuator by a connection spring.
9. A piezoelectric actuator comprising:
an anchor;
an elastic layer having a first end coupled to the anchor, the elastic layer comprising:
a solid sublayer including an elastic material; and
a second sublayer including a plurality of cavities; and
a piezoelectric layer on the second sublayer of the elastic layer, the piezoelectric layer comprising:
a top electrode;
a bottom electrode; and
a piezoelectric material layer between the top electrode and the bottom electrode,
wherein each of the plurality of cavities is characterized by a height greater than a threshold value or greater than a half of a thickness of the solid sublayer.
10. The piezoelectric actuator of claim 9 , wherein the plurality of cavities includes a one-dimensional array or a two-dimensional array of cavities.
11. The piezoelectric actuator of claim 9 , wherein the piezoelectric layer is in physical contact with the second sublayer of the elastic layer.
12. The piezoelectric actuator of claim 9 , wherein:
the elastic layer further comprises a top sublayer on the second sublayer; and
the piezoelectric layer is in physical contact with the top sublayer of the elastic layer.
13. The piezoelectric actuator of claim 9 , wherein:
the elastic layer further comprises a third sublayer including a second plurality of cavities;
the solid sublayer is between the second sublayer and the third sublayer; and
the piezoelectric actuator further comprises a second piezoelectric layer coupled to the third sublayer of the elastic layer.
14. The piezoelectric actuator of claim 9 , wherein:
the elastic layer includes a second movable end opposing the first end; and
the piezoelectric layer is configured to, upon receiving a voltage signal at the top electrode and the bottom electrode, bend the elastic layer such that the second movable end of the elastic layer oscillates at a resonant frequency.
15. The piezoelectric actuator of claim 14 , wherein the resonant frequency is greater than 1 KHz.
16. The piezoelectric actuator of claim 9 , wherein the elastic material includes at least one of polysilicon, silicon oxide, or silicon nitride.
17. The piezoelectric actuator of claim 9 , wherein the piezoelectric material layer includes lead zirconate titanate ceramic.
18. The piezoelectric actuator of claim 9 , wherein the anchor includes a substrate.