Mechanical Mode Imaging of a High-Q Hybrid hBN/Si 3 N 4 Resonator.

We image and characterize the mechanical modes of a 2D drum resonator made of hBN suspended over a high-stress Si 3 N 4 membrane. Our measurements demonstrate hybridization between various modes of the hBN resonator and those of the Si 3 N 4 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 Si 3 N 4 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 Si 3 N 4 membranes for optomechanical or sensing applications.