Characteristics of ZnO/diamond thin films prepared by RF magnetron sputtering

Due to its high Young's modulus, diamond has the highest acoustic wave velo city among all materials and is expected to be a candidate substrate for hi gh-frequency surface acoustic wave (SAW) devices. In this study, the deposi tion of ZnO, as a piezoelectric layer, on a diamond substrate is investigat ed. ZnO has been fabricated by using RF magnetron sputtering with a ZnO tar get and various Ar/O-2 gas ratios, RF powers, and substrate temperatures at a vacuum of 10(-5) Torr. The sputtered ZnO films are characterized by X-ra y diffraction (XRD), Rutherford backscattering spectroscopy (RBS), X-ray ph otoelectron spectroscopy (XPS), and I-V characteristics. All the films show only a (002) orientation, The atomic concentration of the sputtered ZnO fi lms is changed by the oxygen gas ratio, and the ZnO films are grown with a homogeneous composition over their entire thickness. The electrical resisti vity of the films varied from 4x10(3) to 7x10(8) Ohm cm, depending on the A r/O-2 gas ratio. The phase velocity achieved by using the ZnO/IDT/diamond s tructure was about 6,000 m/sec.