Temperature compensation in a semiconductor micromechanical resonator via charge carrier depletion
A semiconductor resonator has a substrate with a thickness extending between a first end and a second end and a pn-junction along the thickness of the substrate forming a free charge carrier depletion region. In another embodiment, a semiconductor resonator has a substrate with a crystal lattice doped at degenerate levels such that the flow of free charge carriers can be minimized. A method of compensating a temperature coefficient of a semiconductor resonator by creating a pn-junction based free charge carrier depletion region within a thickness of a substrate of the resonator is also disclosed.
1. A semiconductor resonator, comprising:
a resonator body having a thickness extending between a first end and a second end; and
a mechanism for reducing a temperature coefficient of frequency of the resonator comprising at least one pn-junction along the thickness of the resonator body forming a free charge carrier depletion region configured for minimizing a flow of free charge carriers therethrough.
2. The resonator of claim 1 , wherein the resonator body comprises doped silicon.
3. The resonator of claim 1 , wherein the resonator body is an n-type substrate.
4. The resonator of claim 1 , wherein the resonator body is an n-type substrate doped with a p-type dopant.
5. The resonator of claim 1 , wherein the resonator body is a phosphorous doped n-type substrate.
6. The resonator of claim 1 , wherein the resonator body is doped with boron.
7. The resonator of claim 1 , wherein the resonator body is a p-type substrate doped with an n-type dopant.
8. The resonator of claim 1 , wherein the resonator body is doped with solid boron.
9. The resonator of claim 1 , wherein the resonator body is doped using liquid boron.
10. The resonator of claim 1 , wherein the resonator body comprises at least one of an n-type or p-type material lightly doped with the other of the n-type or p-type material.
11. The resonator of claim 1 , wherein the resonator body is further defined by a pair of concave surfaces extending between the first and second ends thereof such that the resonator body is wider proximate the ends thereof and narrower proximate a center portion thereof.
12. The resonator of claim 11 , wherein the center portion is approximately two thirds as long as the end regions of the resonator.
13. A semiconductor resonator, comprising:
a resonator body having a thickness extending between a first end and a second end;
a plurality of at least three pn-junction layers along the thickness of the resonator body forming a plurality of at least three free charge carrier depletion regions.
14. The resonator of claim 13 , wherein the resonator body is further defined by a pair of concave surfaces extending between a first end and a second end thereof such that the resonator body is wider proximate the ends thereof and narrower proximate a center portion thereof.
15. A method of compensating a temperature coefficient of a semiconductor resonator, comprising:
A) providing a resonator body having a thickness extending between first and second ends thereof;
B) creating a pry-junction based free charge carrier depletion region along the thickness of the resonator body of the resonator.
16. The method of claim 15 , wherein B) comprises B1) lightly doping the resonator body having at least one of an n-type or p-type material with the other of the n-type or p-type material.
17. The method of claim 16 , wherein B1) comprises:
B1a) doping a phosphorous doped n-type resonator body with a solid p-type dopant; and
B1b) annealing the doped resonator body.
18. The method of claim 16 , wherein B1) comprises:
B1a) doping a phosphorous doped n-type resonator body with a liquid p-type dopant; and
B1b) annealing the doped resonator body.