Research Of ZnO Thin Films For SAW Resonator

Along with the development of informationization detection technology, higher performance and accuracy sensors are needed. SAW sensor detection technology is a relatively new sensing technology, received widespread research for its high sensitivity, small volume and combined of semi-conductor technics. However, both at home and abroad, most of physical and chemical SAW sensors are based on delay line of the oscillators.Compared with SAW delay line (SAWDL) oscillator, the transmission properties of the SAW resonator are very similar with delay line of high Q characteristics. but it has a few important features: One is the resonator insertion loss is much smaller, and the resonators size is much smaller, the other FM range of Saw resonator is much narrow than surface acoustic wave delay linear, and the increasement of FM range will reduce stability.So it is very necessary for researching saw resonators.On the other hand, high-performance ZnO thin film surface acoustic wave components required ZnO films high C axial orientation, grain dense uniform, smooth surface, less defect and high film resistivity.This paper launched a theoretical analysis and research for high frequency saw resonator, and discussed the influence of buffer layer for surface acoustic wave components defects.In this paper, ZnO thin films were deposited on Si(100) substrates,Ti/Si(100) substrates and Au/Si(100) substrates respectively, and the influences of Ti and Au buffer layer on the structure and defect of the ZnO films are discussed. The microstructure, surface roughness, defect and electrical properties of the ZnO films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), photo luminescence (PL) spectroscopy and semiconductor parameters analyzer instrument.The results reveal that the ZnO thin film with Ti buffer layer grown at 350℃exhibits strong c-axis orientation, low root-mean square (RMS) roughness, less defects and high resistivity. This work is of great importance for the defect analysis of piezoelectric films and the development of high-performance ZnO SAW devices.