High Frequency Surface Acoustic Wave Filter Using ZnO/Diamond/Si Structure

Abstract

Diamond films grown by chemical vapor deposition (CVD) method is receiving much attention as surface acoustic wave (SAW) substrate material, due to its remarkable characteristics of large SAW velocity to offer much attraction in fabrication of high frequency SAW devices. The basic properties of SAW propagating in a ZnO/diamond/Si structure were studied utilizing thin film poly-crystalline diamond. Phase velocity, group velocity, electro-mechanical coupling coefficient (K ²), and temperature coefficient of frequency ( TCF) were examined by experiments and theoretical calculations. And it was confirmed that this structure provides high phase velocity up to 10000 m/s, high K ² up to 4.8% and pratical TCF value of -28 ppm/° C. An 1.3 GHz SAW filter of a ZnO/diamond/Si structure was fabricated for the first time.