Piezoelectric thin film element, and piezoelectric thin film device
To stably provide a KNN piezoelectric thin film element having piezoelectric characteristics replaceable with a PZT thin film. A piezoelectric thin film element includes: a piezoelectric thin film on a substrate, having an alkali niobium oxide series perovskite structure expressed by a general formula (K 1-x Na x )NbO 3 (0<x<1), wherein an intensity of a higher angle side skirt field is stronger than an intensity of a lower angle side skirt field of a diffraction peak in a KNN (002) diffraction peak in an X-ray diffraction 2θ/θ pattern of the piezoelectric thin film element.
1. A piezoelectric thin film element comprising: a piezoelectric thin film having an alkali niobium oxide series perovskite structure expressed by a general formula (K 1-x Na x )NbO 3 (0<x<1) provided on a substrate,
wherein the piezoelectric thin film has a KNN (002) diffraction peak of 2θ=43 to 47° in an X-ray diffraction 2θ/θ pattern, and in the KNN (002) diffraction peak, an intensity of a higher angle side skirt field is stronger than an intensity of a lower angle side skirt field; and
wherein a crystal structure of the (K 1-x Na x )NbO 3 (0<X<1) is formed of a phase boundary state of a pseudo-cubic crystal and an orthorhombic crystal.
2. A piezoelectric thin film element comprising: a piezoelectric thin film having an alkali niobium oxide series perovskite structure expressed by a general formula (K 1-x Na x )NbO 3 (0<x<1) provided on a silicon substrate,
wherein the piezoelectric thin film has a KNN (002) diffraction peak of 2θ=43 to 47° in an X-ray diffraction 2θ/θ pattern, and in the KNN (002) diffraction peak, when the diffraction peak angle is denoted by (2θ p ), an angle showing an intensity of 1/20 of the diffraction peak in the lower angle side skirt field is denoted by (2θ L1/20 ), an angle showing the intensity of 1/20 of the diffraction peak in the higher angle side skirt field is denoted by (2θ R1/20 ), and R and L are defined as R=(2θ R1/20 )−(2θ P ), L=(2θ p )−(2θ L1/20 ), a value of R/(R+L) is 0.54 or more; and
wherein a crystal structure of the (K 1-x Na x )NbO 3 (0<X<1) is formed of a phase boundary state of a pseudo-cubic crystal and an orthorhombic crystal.
3. The piezoelectric thin film element according to claim 1 , wherein Na composition ratio x of the piezoelectric thin film having an alkali niobate oxide series perovskite structure expressed by the general formula (K 1-x Na x )NbO 3 (0<x<1), satisfies 0.49≦x≦0.63.
4. The piezoelectric thin film element according to claim 2 , wherein Na composition ratio x of the piezoelectric thin film having an alkali niobate oxide series perovskite structure expressed by the general formula (K 1-x Na x )NbO 3 (0<X<1), satisfies 0.49≦x≦0.63.
5. A piezoelectric thin film device, comprising the piezoelectric thin film element according to claim 1 , wherein the piezoelectric thin film element comprises:
a lower electrode provided between the substrate and the piezoelectric thin film; and
an upper electrode formed on the piezoelectric thin film.
6. A piezoelectric thin film device, comprising the piezoelectric thin film element according to claim 2 , wherein the piezoelectric thin film element comprises:
a lower electrode provided between the substrate and the piezoelectric thin film; and
an upper electrode formed on the piezoelectric thin film.
7. A piezoelectric thin film device, comprising:
the piezoelectric thin film element according to claim 3 ; and
a voltage applying part or a voltage detecting part.
8. A piezoelectric thin film device, comprising:
the piezoelectric thin film element according to claim 4 ; and
a voltage applying part or a voltage detecting part.