Zero Temperature Coefficient Surface-Acoustic-Wave Delay Lines on AlN/Al2O3

We have investigated the temperature dependence of surface acoustic wave (SAW) delay time on AlN films grown by metalorganic chemical vapor deposition (MO–CVD) on the basal plane of sapphire (Al2O3). The temperature coefficient of delay for AlN/Al2O3 structures for SAW propagation along the [11̄00] Al2O3 direction decreased with increasing k H, where k is the wave number and H is the thickness of AlN films. We have succeeded in realizing zero temperature coefficient SAW delay lines at a certain value of k H.