  This work describes the fabrication and characterization of an
Au/ZnO/Pt-based high-overtone bulk acoustic resonator (HBAR) on SiC substrates.
We evaluate its microwave characteristics comparing with Si substrates for
micro-electromechanical applications. Dielectric magnetron sputtering and an
electron beam evaporator are employed to develop highly c-axis-oriented ZnO
films and metal electrodes. The crystal structure and surface morphology of
post-growth layers have been characterized using X-ray diffraction (XRD),
atomic force microscopy (AFM), and scanning electron microscopy (SEM)
techniques. HBAR on SiC substrate results in multiple longitudinal bulk
acoustic wave resonances up to 7 GHz, with the strongest excited resonances
emerging at 5.25 GHz. The value of f.Q (Resonance frequency * Quality factor)
parameter obtained using a novel Q approach method for HBAR on SiC substrate is
4.1 * 10^13 Hz which, to the best of our knowledge, is the highest among all
reported values for specified ZnO-based devices.
