Cost-effective and high frequency surface acoustic wave filters on ZnO:Fe/Si for low-loss and wideband application

ZnO:Fe films with various piezoelectric coefficient d33 were employed to fabricate high frequency surface acoustic wave (SAW) filters on Si by conventional photolithography technology. Comparing with the SAW filters on undoped ZnO films, the electromechanical coupling factor and bandwidth, respectively, increases 75.7% and 14.8%, while the insertion loss decreases 20.3% when using Zn0.988Fe0.012O films with a d33 of ∼127 pC/N. Through annealing demonstration, d33 is considered as the intrinsic factor determining the SAW properties of filters, and the properties are improved by O2 annealing. ZnO:Fe films with enhanced d33 is promising for high frequency, low-loss, and wideband SAW applications.