High-frequency and high-temperature stable surface acoustic wave devices on ZnO/SiO2/SiC structure

Abstract

The explosive growth of wireless communication and the creation of new frequency bands for 5G systems increasingly require surface acoustic wave (SAW) with high operating frequency (i.e. 3–6 GHz) as well as high-temperature stability. In this work, high-frequency and high-temperature stable SAW devices using ZnO/SiO2/SiC layered structures were proposed and reported. SAW characteristics of the Sezawa wave mode, including the phase velocities (Vp), electromechanical coupling coefficients (K2) and temperature coefficient of frequency (TCF), were studied systematically by the finite element method. High-frequency SAW one-port resonators with the resonant frequency ranging from ∼4.5–5.4 GHz were fabricated on the above structures. With SiC substrate providing high velocity and SiO2 interlayer for temperature compensation, a 5.0 GHz and nearly zero TCF of 0.7 ppm °C−1 can be achieved in a SAW device based on ZnO/SiO2/SiC structure. The good performance of these devices demonstrates that the ZnO/SiO2/SiC structure is promising for high-frequency and good temperature-stability SAW device applications.