Gigahertz monolithic delay lines for surface acoustic waves on Silicon

We demonstrate the electrical generation of GHz surface acoustic waves (SAWs) on silicon chips using a process entirely compatible with standard CMOS fabrication. In this process, the interdigitated acoustic transducers are embedded in a silicon dioxide layer, which is subsequently coated with a piezoelectric ZnO film. We show that delay lines with sub-μm wavelength fabricated using this process reach resonance frequencies approaching 4 GHz.