Deposition of piezoelectric AIN thin film on diamond substrate for SHFSAW devices

The preparation of piezoelectric AIN thin films of high quality onto diamond substrates using DC-TFTS method and its application to SHF SAW devices are discussed. FWHM (=3.4 degrees) of the rocking curve of XRD suggested that the caxes of AIN films may well align perpendicular to the film surface. Transversal filters based on Sezawa wave were fabricated to verify whether the prepared AIN/diamond structure can be applied to low loss SAW devices in an SHF range. The propagation loss was experimentally estimated to be 0.08 dB/lambda at the centre frequency of 6.12 GHz. Further reduction in the propagation loss was attempted by using small-grain-diamond substrates.