ZnO-based film bulk acoustic resonator for high sensitivity biosensor applications

Zinc oxide (ZnO)-based film bulk acoustic resonator consisting of a piezoelectric element (Au/ZnO/Pt) and a Bragg reflector (ZnO/Pt multilayer structure) has been fabricated by magnetron sputtering. The transmission electron microscopy and x-ray diffraction measurements revealed that all thin film layers in the device were well crystallized and highly textured. By electrical measurements, it was found that the device had a high resonant frequency (3.94 GHz) and mass sensitivity (8970 Hz cm(2)/ng). The use of the device as a biosensor was demonstrated by comparing the resonant properties of the device with/without coatings of biospecies. (c) 2007 American Institute of Physics.