Abstract:The acoustic characteristics of hybrid SAW/BAW devices based on IDT/ZnO/AlN/Diamond with
layered, etched, and filled structures are investigated using finite element methods.The results indicate that when
hZnO/λ=0.3, hAlN/λ=0.5, and the ZnO piezoelectric film is completely etched (d/hZnO =1), a maximum K2 of
6.54% is obtained for the hybrid SAW/BAW (named quasi-Sezawa wave) excited in etched structure, which is
nearly two times that of the layered SAW structure (d/hZnO =0).The K2 and pressure sensing properties of the
quasi-Sezawa devices are further improved by introducing SiO2 and Diamond fillings.As d/hZnO =1, the pressure
frequency shifts of the quasi-Sezawa device with SiO2 and Diamond fillings are 81.2 kHz/MPa and 207.4 kHz/MPa,
respectively, which are 58.7% and 300% higher than those of the etched structure.Meanwhile, the frequency pressure
coefficient (PCF) of the quasi-Sezawa device with Diamond fillings is 297×10-6/MPa, which is approximately
30% higher than that of the layered SAW structure.It can be concluded that different function sensors based on the
hybrid SAW/BAW can be developed by introducing different fillings.This can have important application prospects
in the fields of pressure, temperature and gas sensing sensors.