Surface acoustic wave characteristics of ZnO films grown on a polycrystalline 3C-SiC buffer layer
Zinc oxide (ZnO) thin films were deposited onto a polycrystalline (poly) 3C-SiC buffer layer for surface acoustic wave (SAW) applications using a magnetron sputtering system. Atomic force microscopy (AFM) and X-ray diffraction (XRD) showed that the ZnO grown on 3C-SiC/Si had a smooth surface, a dominant c-axis orientation and a lower residual stress in ZnO thin film compared to that grown directly onto Si substrate. In order to evaluate the SAW characteristics of ZnO films on a 3C-SiC buffer layer, the two-port SAW resonators, based on inter-digital transducer (IDT)/ZnO/3C-SiC/Si and IDT/ZnO/Si structures, were fabricated and measured within a temperature range of 25135C. The resulting 3C-SiC buffer layer improved the insertion loss by approximately 7.3dB within the SAW resonator and enhanced the temperature stability with TCF=?22ppm/C up to 135C in comparison to that of TCF=?45ppm/C within a temperature range of 25115C of the ZnO/Si structure.
3c-sic buffer layer saw zno thin film resonator