Piezoelectric device and method for producing piezoelectric device
A piezoelectric device that prevents defects due to pyroelectric charge without limiting how the piezoelectric device can be used includes a first metal layer located on a bonding surface of a piezoelectric single crystal substrate. A second metal layer is located on a bonding surface of a support substrate. The first and second metal layers are overlaid on each other to define a metal bonded layer. Subsequently, by oxidizing the metal bonded layer, a semi-conducting layer is formed.
1. A piezoelectric device comprising:
a support substrate;
a first oxide layer stacked on the support substrate;
a semi-conducting layer composed of a semiconductor material or a mixture of a metal and an oxide of the metal and disposed on the first oxide layer;
a second oxide layer stacked on the semi-conducting layer;
a piezoelectric thin film stacked on the second oxide layer; and
a functional electrode disposed on the piezoelectric thin film.
2. The piezoelectric device according to claim 1 , wherein the semi-conducting layer has a volume resistivity of about 1×10 −5 (Ω·m) to about 1×10 2 (Ω·m).
3. The piezoelectric device according to claim 1 , wherein the semi-conducting layer is composed of any one of a titanium oxide, a zinc oxide, a zirconia oxide, a chromium oxide, and silicon, which are semiconductor materials, or any one of a mixture of aluminum and an aluminum oxide, a mixture of cobalt and a cobalt oxide, a mixture of copper and a copper oxide, a mixture of chromium and a chromium oxide, a mixture of iron and an iron oxide, a mixture of molybdenum and a molybdenum oxide, a mixture of nickel and a nickel oxide, a mixture of niobium and a niobium oxide, a mixture of titanium and a titanium oxide, a mixture of silicon and a silicon oxide, a mixture of tantalum and a tantalum oxide, a mixture of tungsten and a tungsten oxide, a mixture of zinc and a zinc oxide, and a mixture of zirconium and a zirconium oxide.
4. The piezoelectric device according to claim 2 , wherein the semi-conducting layer is composed of any one of a titanium oxide, a zinc oxide, a zirconia oxide, a chromium oxide, and silicon, which are semiconductor materials, or any one of a mixture of aluminum and an aluminum oxide, a mixture of cobalt and a cobalt oxide, a mixture of copper and a copper oxide, a mixture of chromium and a chromium oxide, a mixture of iron and an iron oxide, a mixture of molybdenum and a molybdenum oxide, a mixture of nickel and a nickel oxide, a mixture of niobium and a niobium oxide, a mixture of titanium and a titanium oxide, a mixture of silicon and a silicon oxide, a mixture of tantalum and a tantalum oxide, a mixture of tungsten and a tungsten oxide, a mixture of zinc and a zinc oxide, and a mixture of zirconium and a zirconium oxide.
5. The piezoelectric device according to claim 1 , wherein the semi-conducting layer has a thickness of about 100 nm or less.
6. The piezoelectric device according to claim 2 , wherein the semi-conducting layer has a thickness of about 100 nm or less.
7. The piezoelectric device according to claim 3 , wherein the semi-conducting layer has a thickness of about 100 nm or less.
8. The piezoelectric device according to claim 4 , wherein the semi-conducting layer has a thickness of about 100 nm or less.
9. The piezoelectric device according to claim 1 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
10. The piezoelectric device according to claim 2 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
11. The piezoelectric device according to claim 3 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
12. The piezoelectric device according to claim 4 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
13. The piezoelectric device according to claim 5 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
14. The piezoelectric device according to claim 6 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
15. The piezoelectric device according to claim 7 , wherein the piezoelectric thin film is made of a piezoelectric single crystal and has a crystal structure in which film stress differs between a first principal surface side and a second principal surface side of the piezoelectric thin film.
16. The piezoelectric device according to claim 1 , wherein
the first oxide layer is a silicon oxide film; and
the second oxide layer is a silicon oxide film.