Piezoelectric thin film and method for manufacturing the same, and piezoelectric element
A piezoelectric thin film comprising aluminum nitride containing magnesium and hafnium, wherein a content of the hafnium based on 100 atomic % of the magnesium is 8 atomic % or more and less than 100 atomic %, and a total content of the magnesium and hafnium based on a sum of a content of the magnesium, hafnium, and aluminum is in a range of 47 atomic % or less.
1. A piezoelectric film comprising:
aluminum nitride containing magnesium and hafnium, wherein
a content of the hafnium based on 100 atomic % of the magnesium is in a range of 26 atomic % or more and 85 atomic % or less, and
a total content of the magnesium and hafnium based on a sum of a content of the magnesium, hafnium, and aluminum is in a range of 47 atomic % or less.
2. The piezoelectric film according to claim 1 , wherein the total content of the magnesium and hafnium based on the sum of the content of the magnesium, hafnium, and aluminum is in a range of 17 atomic % or more and 38 atomic % or less.
3. A method for manufacturing the piezoelectric film according to claim 1 , the method comprising forming a film by a ternary sputtering method using a first target comprising aluminum, a second target comprising magnesium, and a third target comprising hafnium.
4. The method for manufacturing the piezoelectric film according to claim 3 , wherein the film is formed under a mixed atmosphere of nitrogen gas and argon gas.
5. The method for manufacturing the piezoelectric film according to claim 3 , further comprising:
changing a ratio between a first target power of the first target, a second target power of the second target, and third target power of the third target so as to adjust a content of the aluminum, the magnesium, and the hafnium in the formed film.
6. The method for manufacturing the piezoelectric film according to claim 3 , wherein the film is formed on a substrate, and a temperature of the substrate is from room temperature to 450° C.
7. A method for manufacturing the piezoelectric thin film according to claim 1 , the method comprising:
forming a film by a unitary sputtering method using a target comprising an alloy of aluminum, magnesium, and hafnium.
8. The method for manufacturing the piezoelectric film according to claim 7 , wherein the film is formed under a mixed atmosphere of nitrogen gas and argon gas.
9. The method for manufacturing the piezoelectric film according to claim 7 , further comprising:
changing a content of the aluminum, the magnesium, and the hafnium in the alloy so as to adjust a content of the aluminum, the magnesium, and the hafnium in the formed film.
10. The method for manufacturing the piezoelectric film according to claim 7 , wherein the film is formed on a substrate, and a temperature of the substrate is from room temperature to 450° C.
11. A piezoelectric element comprising:
the piezoelectric film according to claim 1 ; and
first and second electrodes in contact with the piezoelectric film.
12. The piezoelectric element according to claim 11 , wherein
the first electrode is in contact with a first surface of the piezoelectric film, and
the second electrode is in contact with a second surface of the piezoelectric film, the second surface being opposite the first surface.
13. The piezoelectric element according to claim 11 , further comprising:
an acoustic reflection layer adjacent one of the first and second electrodes.