Piezoelectric thin film element
Provided is a piezoelectric thin film device in which lattice mismatch between a piezoelectric thin film and a lower electrode layer (first electrode layer) is reduced. A piezoelectric thin film device 10 comprises a first electrode layer 6 a and a piezoelectric thin film 2 laminated directly on the first electrode layer 6 a ; the first electrode layer 6 a includes an alloy composed of two or more metal elements; the first electrode layer 6 a has a face-centered cubic lattice structure; and the piezoelectric thin film 2 has a wurtzite structure.
1. A piezoelectric thin film device comprising:
a first electrode layer;
a piezoelectric thin film laminated directly on the first electrode layer; and
a second electrode layer laminated on the piezoelectric thin film, wherein
the first electrode layer is a lower electrode layer,
the second electrode layer is an upper electrode layer,
the piezoelectric thin film is held between the first electrode layer and the second electrode layer,
the first electrode layer includes an alloy composed of two or more metal elements,
the first electrode layer has a face-centered cubic lattice structure,
the piezoelectric thin film has a wurtzite structure, and
an insulation resistivity of the piezoelectric thin film to which an electric field of 1 V/μm is applied is 1.0×10 13 Ω·cm or more.
2. The piezoelectric thin film device according to claim 1 , wherein
the alloy includes two or more elements selected from the group consisting of Pt, Ir, Au, Rh, Pd, Ag, Ni, Cu, and Al.
3. The piezoelectric thin film device according to claim 2 , wherein
the alloy is represented by any of the following Chemical Formula 3A, Chemical Formula 3B, Chemical Formula 3C, and Chemical Formula 3D; and
the piezoelectric thin film includes aluminum nitride:
Pd (1-x) Ni x Chemical Formula 3A
wherein the Chemical Formula 3A, 0.03<x<0.46;
Pd (1-x) Ir x Chemical Formula 3B
wherein the Chemical Formula 3B, 0.20<x<1.0;
Ir (1-x) Ni x Chemical Formula 3C
wherein the Chemical Formula 3C, 0≤x≤0.35;
Pt (1-x) Ni x Chemical Formula 3D
wherein the Chemical Formula 3D, 0.11<x<0.50.
4. The piezoelectric thin film device according to claim 2 , wherein
the alloy is represented by any of the following Chemical Formula 4A, Chemical Formula 4B, Chemical Formula 4C, Chemical Formula 4D, Chemical Formula 4E, and Chemical Formula 4F; and
the piezoelectric thin film includes zinc oxide:
Ag (1-y) Pd y Chemical Formula 4A
wherein the Chemical Formula 4A, 0.26<y<1.0;
Ag (1-y) Ni y Chemical Formula 4B
wherein the Chemical Formula 4B, 0.09<y<0.37;
Au (1-y) Pd y Chemical Formula 4C
wherein the Chemical Formula 4C, 0.10<y<0.97;
Au (1-y) Ni y Chemical Formula 4D
wherein the Chemical Formula 4D, 0.04<y<0.33;
Pt (1-y) Pd y Chemical Formula 4E
wherein the Chemical Formula 4E, 0<y<0.80;
Pt (1-y) Ni y Chemical Formula 4F
wherein the above Chemical Formula 4F, 0<y<0.07.
5. The piezoelectric thin film device according to claim 1 , wherein
the alloy includes three or more elements selected from the group consisting of Pt, Jr, Au, Rh, Pd, Ag, Ni, Cu, and Al.
6. The piezoelectric thin film device according to claim 5 , wherein
the alloy is represented by any one of the following Chemical Formula 6A and Chemical Formula 6B; and
the piezoelectric thin film includes aluminum nitride:
Pd x Ni y Ir z Chemical Formula 6A
wherein the Chemical Formula 6A, 0<x<0.97, 0<y<0.46, and 0<z<1.0; and
Pd x Ni y Pt z Chemical Formula 6B
wherein the Chemical Formula 6B, 0<x<0.97, 0.03<y<0.5, and 0<z<0.89.
7. The piezoelectric thin film device according to claim 5 , wherein
the alloy is represented by any of the following Chemical Formula 7A, Chemical Formula 7B, and Chemical Formula 7C; and
the piezoelectric thin film includes zinc oxide:
Pd x Ni y Pt z Chemical Formula 7A
wherein the Chemical Formula 7A, 0<x<0.80, 0<y<0.07, and 0.2<z<1.0;
Pd x Ni y Ag z Chemical Formula 7B
wherein the Chemical Formula 7B, 0<x<0.96, 0<y<0.37, and 0.04<z<0.91;
Pd x Ni y Au z Chemical Formula 7C
wherein the Chemical Formula 7C, 0<x<0.97, 0<y<0.33, and 0.03<z<0.96.
8. The piezoelectric thin film device according to claim 1 , wherein
a (111) plane of the face-centered cubic lattice structure of the first electrode layer is oriented in a normal direction of an interface between the first electrode layer and the piezoelectric thin film.
9. The piezoelectric thin film device according to claim 1 , wherein
a degree of lattice mismatch between the first electrode layer and the piezoelectric thin film is 0% or more and 2% or less.
10. The piezoelectric thin film device according to claim 1 , wherein
a content of Al in the first electrode layer is 0 atomic % or more and less than 90 atomic %.
11. A piezoelectric thin film device comprising:
a first electrode layer;
a piezoelectric thin film laminated directly on the first electrode layer; and
a second electrode layer laminated on the piezoelectric thin film, wherein
the first electrode layer is a lower electrode layer,
the second electrode layer is an upper electrode layer,
the piezoelectric thin film is held between the first electrode layer and the second electrode layer,
the first electrode layer includes an alloy composed of two or more metal elements,
the first electrode layer has a face-centered cubic lattice structure,
the piezoelectric thin film has a wurtzite structure, and
a free energy change AG in an oxidation reaction of the alloy is a negative value and −226.81 kJ/mol or more.
12. The piezoelectric thin film device according to claim 1 , wherein
a full width at half maximum of a rocking curve of a (002) plane of the piezoelectric thin film is 2.0° or less.
13. A piezoelectric thin film device comprising:
a first electrode layer;
a piezoelectric thin film laminated directly on the first electrode layer; and
a second electrode layer laminated on the piezoelectric thin film, wherein
the first electrode layer is a lower electrode layer,
the second electrode layer is an upper electrode layer,
the piezoelectric thin film is held between the first electrode layer and the second electrode layer,
the first electrode layer includes an alloy composed of two or more metal elements,
the first electrode layer has a face-centered cubic lattice structure,
the piezoelectric thin film has a wurtzite structure, and
a piezoelectric constant d 33 of the piezoelectric thin film is 6.0 pC/N or more.
14. The piezoelectric thin film device according to claim 1 , wherein
the piezoelectric thin film covers the entire surface of the first electrode layer.