High velocity SAW using aluminum nitride film on unpolished nucleation side of freestanding CVD diamond

High performances surface acoustic wave filters based on AlN/diamond layered structure were performed. C-axis oriented aluminum nitride films with various thicknesses were sputtered on unpolished nucleation side (NS) of freestanding polycrystalline CVD diamond obtained by silicon substrate etching. Experimental results show that high order modes as well as Rayleigh waves are excited. Experimental results are in a good agreement with the calculated dispersion curves which were determined by software simulation with Green's function formalism. We demonstrate clearly that SAW devices combining high phase velocity, high electromechanical coupling coefficient and low temperature coefficient can be performed with AlN/diamond structure.