High-Frequency Surface Acoustic Wave Devices Based on ZnO/SiC Layered Structure

Abstract

In this letter, highly (0002) oriented ZnO piezoelectric films were deposited on high acoustic velocity SiC substrates. Surface acoustic wave (SAW) devices on ZnO/SiC layered structure operating in the fundamental mode with high frequency to the 7-GHz range were successfully fabricated for the first time. The comprehensive experimental and theoretical investigations about phase velocities ${V}_{p}$ , the electromechanical coupling coefficients ${K}^{{2}}$ , and quality factors Q of one-port SAW resonators have been studied considering various ZnO normalized thicknesses ${h}/\lambda $ . The resonators with large ${K}^{{2}}$ and high Q are implemented over 5–7 GHz demonstrating ${K}^{{2}}$ of 0.47%–2.83% and Q of 146–549. Specifically, a high ${K}^{{2}}$ of 2.83% and a large Q of 549 are simultaneously achievable for the resonator at 5.19 GHz. Finally, with the high ${V}_{p}$ of ZnO/SiC structure being up to 6800 m/s at ${h}/\lambda = {0.14}$ , a 6.8-GHz SAW filter was achieved. Our work shows that the ZnO/SiC structure is of great potential for high-frequency SAW devices application.