SAW resonators of SiO/sub 2//ZnO/diamond structure in GHz range

Surface acoustic wave (SAW) characteristics of the SiO/sub 2//in interdigital-transducer(IDT)/ZnO/diamond structure were studied, and it was found that the 2nd Sezawa mode in this structure can provide superior SAW characteristics of a zero temperature coefficient of frequency (TCF), a high velocity of 10,000 m/s and a large electromechanical coupling coefficient of 1.2%. Several kinds of SAW resonators were successfully fabricated with this structure, which resulted in superior characteristics with the minimum insertion losses from 6.7 to 13.4 dB, Q values from 680 to 1600, at the center frequencies of 2.488, 2.666 and 3.061 GHz. Their frequency shifts in the temperature range from 0 to 85/spl deg/C were no more than 50 ppm which is smaller than those of ST-cut quartz or 36Y-cut quartz. These characteristics are superior to those ever realized for a GHz SAW resonator.