Low loss diamond SAW devices by small grain size poly-crystalline diamond

We have successfully developed a poly-crystalline diamond film whose grain size is small, which is expected to have a low propagation loss in SAW devices. Using this diamond film, three kinds of narrow band SAW filters of the SiO/sub 2//ZnO/diamond/Si structure were fabricated with the center frequency from 2.5 to 5.0 GHz and the propagation losses in these filters were investigate. It was confirmed that the propagation loss with this diamond film is about two thirds of that with our previously studied diamond film.