A lower electrode is formed on a silica glass substrate or a stainless
substrate. Through a sputtering process, a thin film of aluminum nitride
and/or zinc oxide is formed on the lower substrate so that the degree of
dipole-orientation becomes 55% or more, and thereby a piezoelectric thin
film is formed. And an upper electrode is formed on the piezoelectric
thin film.A piezoelectric device has a piezoelectric layer made of
aluminum nitride and/or zinc oxide. Aluminum nitride and zinc oxide with
a crystal structure have inborn piezoelectric characteristics because
their crystal structures are not symmetrical, they do not have Curie
temperature unlike ferroelectrics, and in aluminum nitride and zinc
oxide, magnetic transition does not occur even at high temperature, so
that they never lose piezoelectric characteristics until crystal melts or
sublimates.