High velocity pseudo-SAWs on CVD diamond substrate

In recent years high frequency SAW devices for GHz range telecommunication applications have been demonstrated using multilayer structures containing a high velocity CVD diamond thin-film on silicon substrate. Despite a theoretical sound velocity of diamond approaching 18000 m/s, the silicon substrate considerably increases the propagation loss and prohibits the high velocity modes to be effectively used, unless the diamond thin-film is thick compared with acoustic wavelengths or a submicron lithography is involved. Instead of growing diamond thin-film on silicon substrate, this work reports a delay-line structure fabricated with ZnO thin-film on a thick CVD diamond substrate (380 μm). A high velocity pseudo-SAWs (HVPSAWs) mode in excess of 15000 m/s with a propagation loss less than 0.58 dB/λ was observed. The device structure allows an investigation of high-velocity and low-coupling propagation modes for SAWs