Single InAs Nanowire Hypersonic Acoustic Nanoresonator.

We report acoustic oscillations in suspended single InAs nanowire resonators at hypersonic frequencies, measured via all-optical time-resolved microscopy. Two distinct oscillations, attributed to the fundamental longitudinal extensional and radial breathing modes, are observed with frequencies reaching tens of GHz. The measured frequencies are in good agreement with finite element method simulations, validating the stiffness matrix for wurtzite InAs nanowires proposed in a recent work. This achievement is crucial for device development, enabling accurate nanoresonator modeling. The acoustic time attenuation rate and the reciprocal quality factor of the radial breathing mode are found to scale linearly with the fraction of nanowire length in contact with the substrate, indicating that extrinsic acoustic damping is the dominant attenuation mechanism in our experiments. This finding indicates that optimizing the clamping design should be more effective in further enhancing the quality factor of the nanoresonator than improving the crystal quality of the InAs nanowire. These results pave the way for the development of high-performance hypersonic semiconductor nanoresonators and optomechanical nanotransducers.