Piezoelectric thin film element, and piezoelectric thin film device
View Patent ↗Disclosed are a piezoelectric thin film element and a piezoelectric thin film device which have improved piezoelectric properties and high performance and can be produced in improved yields. The piezoelectric thin film element ( 1 ) comprises: a substrate ( 10 ), and a piezoelectric thin film ( 40 ) which is arranged on the substrate ( 10 ), has at least one crystal structure represented by general formula (Na x K y Li z )NbO 3 (0≦x≦1, 0≦y≦1, 0≦z≦0.2, x+y+z=1) and selected from the group consisting of pseudo-cubic crystal, a hexagonal crystal, and an orthorhombic crystal, and contains an inert gas element at a ratio of 80 ppm or less by mass.
1. A piezoelectric thin film element, comprising:
a substrate; and
a piezoelectric thin film provided on the substrate,
wherein the piezoelectric thin film has at least one crystal structure represented by the general formula (Na x K y Li z )NbO 3 (0≦x≦1, 0≦y≦1, 0≦z≦0.2, x+y+z=1), and selected from the group consisting of a pseudocubic crystal, a tetragonal crystal, and an orthorhombic crystal, and contains a mass ratio of an inert gas element of not more than 80 ppm.
2. The piezoelectric thin film element according to claim 1 , wherein
the piezoelectric thin film contains a not less than 30 ppm and not more than 70 ppm of the inert gas element.
3. The piezoelectric thin film element according to claim 1 , wherein
the piezoelectric thin film contains a not more than 0.16 μg/cm 2 of the inert gas element.
4. The piezoelectric thin film element according to claim 3 , wherein
the piezoelectric thin film contains a not less than 0.06 μg/cm 2 and not more than 0.15 μg/cm 2 of the inert gas element.
5. The piezoelectric thin film element according to claim 1 , wherein
the inert gas element is argon (Ar).
6. The piezoelectric thin film element according to claim 1 , further comprising
a lower electrode between the substrate and the piezoelectric thin film.
7. The piezoelectric thin film element according to claim 6 , wherein
the lower electrode includes an electrode layer formed of Pt or a Pt containing alloy.
8. The piezoelectric thin film element according to claim 6 , wherein
the lower electrode includes a single crystalline oriented layer oriented preferentially in a perpendicular direction to a surface of the substrate.
9. The piezoelectric thin film element according to claim 1 , wherein
the piezoelectric thin film includes strain parallel to a surface of the substrate.
10. The piezoelectric thin film element according to claim 9 , wherein
the strain is strain due to tensile or compressive stress.
11. The piezoelectric thin film element according to claim 1 , wherein
the piezoelectric thin film includes inhomogeneous strain in a perpendicular or parallel direction, or perpendicular and parallel directions, to a surface of the substrate.
12. A piezoelectric thin film device, comprising:
the piezoelectric thin film element according to claim 1 ; and
a voltage applying portion which applies voltage to the piezoelectric thin film element.
13. A piezoelectric thin film device, comprising:
the piezoelectric thin film element according to claim 1 ; and
a voltage detecting portion which detects voltage applied to the piezoelectric thin film element.