Epitaxial piezoelectric layer SMR fabricated using epitaxial sacrificial layer process

Single crystalline piezoelectric layer is expected to possess higher power durability and Q factor than polycrystalline because the dielectric and mechanical loss increases due to the grain boundary. In this study, we introduce a method to fabricate epitaxial piezoelectric layer on acoustic Bragg reflector using wet etching of epitaxial sacrificial layer. First, (0001) ZnO epitaxial films were grown on epitaxial (111) Au / (111) Pt / (0001) sapphire substrate by magnetron sputtering. Next, the polycrystalline Pt bottom electrode and the acoustic Bragg reflector based on 2 pairs of SiO2 / Mo were deposited on ZnO epitaxial films. After etching Au epitaxial sacrificial layer, SMR based on Au / epitaxial ZnO / Pt / Bragg reflector were fabricated. The crystallinity of epitaxial layers was determined by X-ray diffraction. FWHM values of the ω-scan rocking curves of Pt, Au and ZnO were determined as 0.25°, 0.27° and 0.80°, respectively. Moreover, six symmetry was clearly observed in Pt, Au and ZnO epitaxial layers. Real part of impedance characteristics of resonator was measured by a network analyzer. Resonance peak was observed at 1.3 GHz.