Study of ZnO thin films grown by PLD on (100) Si for surface acoustic wave devices

ZnO thin films were deposited on Si (100) substrates using Pulsed Laser Deposition at 600 /spl deg/C and an oxygen pressure of 1 e-4 Torr. Inorder to improve the ZnO film quality for SAW device applications, buffer layers of ZnO and ZnO/Indium Tin Oxide(ITO) alternating layers were grown on Si (100). High-resolution X-ray photoelectron spectroscopy (XPS) indicated a binding energy of Zn(2p/sup 3/) at 1021.4 eV and O (1s) at 530.5 eV and ascertained the film composition. The quality of crystalline growth was determined using X-ray diffraction (XRD) and photoluminescence measurements. SAW filters having inter-digitated (IDT) finger widths of 1/spl mu/m and finger spacing of 2.5 /spl mu/m, were fabricated on films with different buffer layers. The input and output IDTs were composed of a 500 /spl mu/m thick layer of Al, which was deposited using e-beam evaporation. Scanning electron microscopy (SEM) images of the SAW devices indicated the high quality photolithography. The center frequency of the SAW filters has been designed to be in the GHz range by improving ZnO film quality on Si (100) substrate, and the geometry and lithography of the device. The devices are capable of ultra high frequency response suitable for secure mobile communication systems and high performance sensors.