• Kuo-Sheng Kao, Chien-Chuan Cheng, and Ying-Chung Chen.
• Department of Electrical Engineering, National Sun Yat-Sen University, Kaohsiung, Taiwan, ROC.
• IEEE Trans Ultrason Ferroelectr Freq Control. 2002 Mar 1; 49 (3): 345-9.

AbstractThe c-axis-oriented aluminum nitride (AIN) films were deposited on z-cut lithium niobate (LiNbO3) substrates by reactive RF magnetron sputtering. The crystalline orientation of the AIN film determined by x-ray diffraction (XRD) was found to be dependent on the deposition conditions such as substrate temperature, N2 concentration, and sputtering pressure. Highly c-axis-oriented AIN films to fabricate the AIN/LiNbO3-based surface acoustic wave (SAW) devices were obtained under a sputtering pressure of 3.5 mTorr, N2 concentration of 60%, RF power of 165 W, and substrate temperature of 400 degrees C. A dense pebble-like surface texture of c-axis-oriented AIN film was obtained by scanning electron microscopy (SEM). The phase velocity and the electromechanical coupling coefficient (K2) 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/ degrees C.

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