Abstract
ZnO films with c-axis (0002) orientation have been successfully grown by RF magnetron sputtering on interdigital transducer (IDT)/Al_2O_3/SiO_2/Si substrates. The Al_2O_3 films were deposited on SiO_2/Si substrates by electron beam evaporation. Crystalline structures of the films were investigated by X-ray diffraction, atomic force microscopy and scanning electron microscopy. The 2^<nd>-order phase velocity of the surface acoustic wave (SAW) device with a 7.5μm thick Al_2O_3 buffer layer was measured to be about 5432m/s, which approaches that (5840m/s) of ZnO/IDT/sapphire. The experimental result is beneficial to replace the expensive single crystalline sapphire substrate with Al_2O_3 buffer layer at lower cost for the high frequency SAW devices, and is also useful to integrate the semiconductor and high frequency SAW devices on the same Si substrate.
