Fabrication and characterization of ZnO piezoelectric films for sensor devices

Films of ZnO grown by planar magnetron sputtering have excellent qualities: 1) c-axis orientation of the ZnO film of such presision that the angular distribution of c-axis is smaller than 1° across a 4cm field for a 10cm target, 2) uniform etch properties over the same area indicating that the piezoelectric polarity is the same over the film, 3) thicknesses up to 48µm with a transparency and surface smoothness similar to those of a glass substrate, 4) an optical waveguide loss for the TE0mode of He-Ne 6328Å line as low as 2.1dB/ cm in a 3.2µm thick film without post-sputtering treatment, 5) effective surface wave coupling coefficients greater than 90% of the theoretical values of ZnO/substrate composite with a high reproducibility, 6) a sputtering rate as high as 10µm/h without metal backing on ZnO ceramic target without reducing the film quality.