Surface acoustic wave bandpass filters properties of AlN thin films sputtered on LiNbO/sub 3/ substrates

摘要

Surface acoustic wave (SAW) filter properties such as center frequency (F/sub c/) and 3dB bandwidth of aluminum nitride (AlN) thin films sputtered on z-cut LiNbO/sub 3/ substrates were investigated. Highly c-axis prefer-oriented AlN thin films deposited on z-cut LiNbO/sub 3/ substrates were obtained by reactive rf magnetron sputtering. The results of our experiments showed that F/sub c/ of SAW filter was increased significantly for the increase of h//spl lambda/, where h was the AlN film thickness and /spl lambda/ was the wavelength of SAW. Comparing the SAW propagate along with the z-cut LiNbO/sub 3/ single crystal, the AlN/LiNbO/sub 3/ based surface acoustic wave (SAW) devices could improve the velocity of SAW. The 3dB bandwidth of SAW filter was decreased by the increase of h//spl lambda/ meaning that frequency selection getting stricter.