SAW devices on diamond

SAW characteristics in a ZnO/diamond/Si structure were investigated by theoretical calculations and experiments using poly-crystalline diamond films. It was found that the 1st mode in the ZnO/IDT/diamond/Si structure has the velocity of 10,500 m/s and K² value of 1.5%, and the 2nd mode in the IDT/ZnO/diamond/Si structure has the velocity of 11,600 m/s and K² value of 1.1%. The experimental results agreed well with the calculated data. Utilizing this high velocity, a 2.5 GHz filter was fabricated with 1 μm line-and-space IDTs with the ZnO/IDT/diamond/Si structure. Propagation loss was confirmed to be much lower than ever reported for a ZnO/glass structure. It was also found by calculations that a SiO₂ /ZnO/diamond/Si structure realizes a zero TCD value with the velocity of 10,700 m/s and the K² value of 0.78% and that a LiNbO₃/diamond/Si structure has a high velocity of 12,000 m/s and a large K² value of 9%. These structures including a diamond layer can be effectively used for a variety of applications in GHz range with much higher velocities than those of conventional SAW materials such as LiTaO₃, LiNbO₃ or quartz