Gallium nitride structure, piezoelectric element, method of manufacturing piezoelectric element, and resonator using piezoelectric element
A gallium nitride structure that includes: a substrate; a gallium nitride layer opposed to the substrate and containing gallium nitride as a main component thereof; and a first electrode between the gallium nitride layer and the substrate. The first electrode includes at least one hafnium layer containing a single metal of hafnium as a main component thereof, and the at least one hafnium layer is in contact with the gallium nitride layer.
1. A gallium nitride structure, comprising:
a substrate;
a gallium nitride layer provided so as to be opposed to the substrate and containing gallium nitride as a main component; and
a first electrode that is provided between the gallium nitride layer and the substrate, the first electrode including at least one hafnium layer containing a single metal of hafnium as a main component thereof, and the at least one hafnium layer in contact with the gallium nitride layer.
2. A gallium nitride structure, comprising:
a substrate;
a gallium nitride layer provided so as to be opposed to the substrate and containing gallium nitride as a main component; and
a first electrode that is provided between the gallium nitride layer and the substrate, the first electrode including at least one hafnium layer containing hafnium as a main component thereof the at least one hafnium layer in contact with the gallium nitride layer,
wherein the at least one hafnium layer includes:
a first hafnium layer that is in contact with the substrate;
a second hafnium layer that is in contact with the gallium nitride layer; and
a metal layer having a resistivity lower than hafnium between the first hafnium layer and the second hafnium layer.
3. The gallium nitride structure according to claim 2 , wherein the metal layer is an aluminum layer containing aluminum as a main component thereof.
4. The gallium nitride structure according to claim 2 , further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween.
5. The gallium nitride structure according to claim 1 , further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween.
6. The gallium nitride structure according to claim 1 , wherein the substrate comprises a degenerated n-type Si.
7. A resonator comprising:
a vibration portion comprising the gallium nitride structure according to claim 1 ;
a holding portion surrounding the vibration portion; and
a holding arm connecting the vibration portion to the holding portion.
8. A resonator comprising:
a vibration portion comprising the gallium nitride structure according to claim 2 ;
a holding portion surrounding the vibration portion; and
a holding arm connecting the vibration portion to the holding portion.
9. The resonator according to claim 8 , wherein the metal layer is an aluminum layer containing aluminum as a main component thereof.
10. The resonator according to claim 8 , further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween.
11. The resonator according to claim 7 , further comprising a second electrode opposed to the first electrode with the gallium nitride layer therebetween.
12. The resonator according to claim 7 , wherein the substrate comprises a degenerated n-type Si.
13. A method of manufacturing a piezoelectric element, the method comprising:
forming a first electrode including a hafnium layer containing a single metal of hafnium as a main component thereof on a substrate by sputtering; and
forming a piezoelectric body layer containing gallium nitride as a main component thereof on the first electrode by sputtering.
14. The method of manufacturing a piezoelectric element according to claim 13 , wherein the piezoelectric body layer is formed at a temperature of 500° C.
15. The method of manufacturing a piezoelectric element according to claim 13 , wherein the forming of the first electrode includes:
forming a first hafnium layer on the substrate;
forming a metal layer having a resistivity lower than hafnium on the first hafnium layer; and
forming a second hafnium layer on the metal layer.
16. The method of manufacturing a piezoelectric element according to claim 15 , wherein the metal layer is an aluminum layer containing aluminum as a main component thereof.
17. The method of manufacturing a piezoelectric element according to claim 15 , further comprising forming a second electrode on the piezoelectric body layer.
18. The method of manufacturing a piezoelectric element according to claim 13 , further comprising forming a second electrode on the piezoelectric body layer.
19. The method of manufacturing a piezoelectric element according to claim 13 , wherein the substrate comprises a degenerated n-type Si.