The highly c-axis-oriented AlN buffer layers were successfully deposited on the nucleation sides of free-standing diamond (FD) films by direct current (DC) magnetron sputtering method. The influence of the sputtering parameters, such as the gas pressure and the sputtering plasma composition of Ar-to-N2, on the properties of AlN thin films were investigated. X-ray diffraction (XRD) measurements showed that when the gas pressure was 0.2 Pa and the plasma composition of Ar-to-N2 was 3:1, the higher intensity of the (002) diffraction peak and the narrower full width at half maximum (FWHM) were detected, which meant high c-axis orientation and high quality of AlN films. At last, a ZnO thin film was deposited on this buffer layer. The XRD and AFM results indicated that the sandwich structure can satisfy the application of surface acoustic wave (SAW) devices.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.