J042034 Excitation of Ultrahigh-Frequency Surface Acoustic Wave Resonance with Cu Nanowires and Its Dispersion Characteristics

Abstract

We present an ultrahigh frequency surface acoustic wave (SAW) resonance phenomenon. We fabricated Cu nanowire specimen on (100) Si and glass substrate, and generate vibrations related with nanowires by picosecond ultrasound method. We succeeded in observing high (70-80 GHz) and low (-15GHz) frequency vibrations. They are identified to be thickness resonance of nanowires and SAW resonances, respectively. By changing the wire spacing, we observed dispersion relationship of the ultrahigh SAW and compared them with calculations with the effective mass density by considering the volume fraction of nanowire. This calculation showed good agreements with the measurements when the penetration depth of SAW energy is 6% of wavelength.