Piezoelectric aluminum nitride thin films were deposited by reactive dc magnetron sputtering under various experimental conditions on a silicon. (100) substrates. These films structural and microstructural properties were studied using x-ray diffraction (XRD), selected area electron diffraction (SAED), and transmission electron microscopy (TEM) in order to determine the optimum growth conditions that improve the piezoelectric coupling. A highly c-axis oriented AIN film (002) was identified from XRD and SAED. An average grain column size of about 40 nm was determined from TEM. The root-mean-square surface roughness measured using atomic-force microscopy was less than 7 nm. The optimum experimental parameters found for AIN deposition on Si(100) substrates were then extrapolated to its deposition on a ST-cut quartz substrate for the investigation of the influence of substrates on the surface acoustic wave (SAW) propagation. The AIN/Si and AIN/ST-quartz SAW devices were formed using the photolithography process. Their operating characteristics, phase velocity, temperature coefficient of frequency, and electromechanical coefficient (K-2) were measured and analyzed. Experimental results show that the generalized SAW (GSAW) as well as the pseudosurface acoustic wave were excited in this structure. Their phase velocities are, respectively, 3245 m/s and 5117 m/s. The SAW device realized from the AIN/ST-cut quartz structure exhibits higher phase velocity and higher K-2 compared to those formed on the ST-quartz substrate. (C) 2004 American Vacuum Society.