<p>Disclosed herein is a zinc oxide piezoelectric crystal film which is grown on an R-plane sapphire substrate to orient its c-axis in parallel with the substrate surface. In order to improve orientation of the zinc oxide piezoelectric crystal film, a Zn target for forming the zinc oxide piezoelectric crystal film by sputtering contains not more than 5 percent by weight of nickel or not more than 4.5 percent by weight of iron with respect to Zn. <IMAGE></p>
