Mechanical Mode Imaging of a High-Q Hybrid hBN/SiN Resonator.

We image and characterize the mechanical modes of a 2D drum resonator made of hBN suspended over a high-stress SiN membrane. Our measurements demonstrate hybridization between various modes of the hBN resonator and those of the SiN membrane. The measured resonance frequencies and spatial profiles of the modes are consistent with finite-element simulations based on idealized geometry. Spectra of the thermal motion reveal that, depending on the degree of hybridization with modes of the heavier and higher-quality-factor SiN membrane, the quality factors and the motional mass of the hBN drum modes can be shifted by orders of magnitude. This effect could be exploited to engineer hybrid drum/membrane modes that combine the low motional mass of 2D materials with the high quality factor of SiN membranes for optomechanical or sensing applications.