Sezawa wave on ZnO/sapphire substrate is applied to low insertion loss surface acoustic wave (SAW) filters in microwave band of 1.5 GHz to 2.5 GHz range. RF planar magnetron sputtering (RF-Mg) system is used for the fabrication of epitaxial ZnO film. Sputtering conditions and the dopant are decided to realize stable and reproducible process. Details of ZnO epitaxial growth and practical application results are reviewed. To improve the piezoelectric properties of ZnO film, electron cyclotron resonance (ECR) sputtering method is investigated. ZnO/quartz substrate has small temperature coefficient of frequency (TCF) and medium electromechanical coupling coefficient (ks) comparable to ST cut quartz and Li2B4O7 respectively. Theoretical and experimental results are also discussed.
ASJC Scopus subject areas
- Acoustics and Ultrasonics