Surface acoustic wave (SAW) devices based on an aluminum nitride (AIN)/diamond layered structure are attractive due to their high operating frequency. To enhance the operating frequency of a diamond SAW device, we demonstrated one piezoelectric layer on diamond by doping AIN with boron. In this study, highly c-axisoriented wurtzite boron-aluminum nitride (B, Al)N films were deposited on diamond by a co-sputtering technique. The resulting films exhibit a higher piezoelectric coefficient d(33) and higher Young's modulus than AIN films. Moreover, the greater rigidity of (B, Al)N film further boosts the resonance frequency of a diamond SAW device. Considering the SAW wavelength (lambda = 21 mu m), the calculated surface acoustic velocities (V-S) of (B, Al)N on diamond is 8860 m/s that is higher than AIN on diamond (8720 m/s). We also find that the electromechanical coupling coefficient (K-2) of a SAW device based on (B. Al)N on diamond was the same (similar to 0.5%) as that of one based on AIN on diamond. (C) 2011 Elsevier B.V. All rights reserved.