Title :
Synthesis and surface acoustic wave properties of AlN films deposited on LiNbO/sub 3/ substrates
Author :
Kao, Kuo-Sheng ; Cheng, Chien-Chuan ; Chen, Ying-Chung
Author_Institution :
Dept. of Electr. Eng., Nat. Sun Yat-Sen Univ., Kaohsiung, Taiwan
fDate :
3/1/2002 12:00:00 AM
Abstract :
The c-axis-oriented aluminum nitride (AlN) films were deposited on z-cut lithium niobate (LiNbO/sub 3/) substrates by reactive RF magnetron sputtering. The crystalline orientation of the AlN film determined by x-ray diffraction (XRD) was found to be dependent on the deposition conditions such as substrate temperature, N/sub 2/ concentration, and sputtering pressure. Highly c-axis-oriented AlN films to fabricate the AlN/LiNbO/sub 3/-based surface acoustic wave (SAW) devices were obtained under a sputtering pressure of 3.5 mTorr, N/sub 2/ concentration of 60%, RF power of 165 W, and substrate temperature of 400/spl deg/C. A dense pebble-like surface texture of c-axis-oriented AlN film was obtained by scanning electron microscopy (SEM). The phase velocity and the electromechanical coupling coefficient (K/sup 2/) of SAW were measured to be about 4200 m/s and 1.5%, respectively. The temperature coefficient of frequency (TCF) of SAW was calculated to be about -66 ppm//spl deg/C.
Keywords :
X-ray diffraction; aluminium compounds; lithium compounds; scanning electron microscopy; sputtered coatings; surface acoustic waves; surface texture; 165 W; 3.5 mtorr; 400 C; AlN-LiNbO/sub 3/; RF magnetron sputtering; X-ray diffraction; aluminum film; crystalline orientation; electromechanical coupling coefficient; lithium niobate substrate; phase velocity; scanning electron microscopy; surface acoustic wave properties; surface texture; temperature coefficient of frequency; Acoustic waves; Aluminum nitride; Lithium niobate; Radio frequency; Scanning electron microscopy; Sputtering; Substrates; Surface acoustic wave devices; Surface acoustic waves; Temperature; Acoustics; Aluminum Compounds; Crystallography, X-Ray; Equipment Design; Materials Testing; Microwaves; Models, Theoretical; Niobium; Oxides; Sensitivity and Specificity; Substrate Specificity; Temperature; Transducers;
Journal_Title :
Ultrasonics, Ferroelectrics, and Frequency Control, IEEE Transactions on
