Alkali-niobate-based piezoelectric thin film element
An alkali-niobate-based piezoelectric thin film element includes a substrate, a lower electrode film on the substrate, a piezoelectric thin film on the lower electrode film, and an upper electrode film on the piezoelectric thin film. The piezoelectric thin film is made of an alkali-niobate-based piezoelectric material represented by the formula (Na x K y Li z )NbO 3 , where 0≦x≦1, 0≦y≦1, 0≦z≦0.2, and x+y+z=1. The piezoelectric thin film has an element pattern and contains a metal element in a higher concentration near the upper electrode film than near the lower electrode film. The average concentration of the metal element is 5×10 17 atoms/cm 3 or less in a region within ±15% of the thickness of the piezoelectric thin film from a position corresponding to half the thickness of the piezoelectric thin film.
1. An alkali-niobate-based piezoelectric thin film element comprising:
a substrate;
a lower electrode film on the substrate;
a piezoelectric thin film on the lower electrode film, the piezoelectric thin film comprising an alkali-niobate-based piezoelectric material represented by the formula (Na x K y Li z )NbO 3 , where 0≦x≦1, 0≦y≦1, 0≦z≦2, and x+y+z=1; and
an upper electrode film on the piezoelectric thin film, wherein
the piezoelectric thin film has a desired micro pattern formed for a piezoelectric element and contains a metal element in a higher concentration near the upper electrode film than near the lower electrode film, the metal element being chromium, gold or platinum, and
the average concentration of the metal element is 5×10 17 atoms/cm 3 or less in a region within ±15% of the thickness of the piezoelectric thin film from a position corresponding to half the thickness of the piezoelectric thin film.
2. The alkali-niobate-based piezoelectric thin film element according to claim 1 , wherein the average concentration of the metal element is 1×10 17 atoms/cm 3 or more in the region within ±15% of the thickness of the piezoelectric thin film from the position corresponding to half the thickness of the piezoelectric thin film.
3. An electronic device comprising the alkali-niobate-based piezoelectric thin film element according to claim 1 .