Surface acoustic wave devices on AlN/Single-Crystal Diamond for high frequency and high performances operation

In this paper we present recent results on fabrication of SAW devices on AlN/single-crystal diamond. The AlN thin film was deposited by sputtering technique, optimized to achieve an high degree of orientation value of the c-axis perpendicular to the plate surface (rocking curve FWHM approximate to 3.5 degrees), while the single-crystal diamond was grown by Microwave Plasma Chemical Vapor Deposition (MWPECVD) on High Pressure High Temperature (HPHT) diamond substrate. SAW propagation on the structure has been theoretically investigated and experimentally verified by implementing both delay-lines and 1-port resonators at different normalized AlN thickness (h/lambda). Very good accordance is obtained between evaluated phase velocity dispersion curves and measured values. Frequency responses show low insertion losses and rather high Q factors, respectively, for delay-lines and resonators. Pseudo-SAW modes are also observed and reported.