Mechanical mode imaging of a high-Q hybrid hBN/Si$_3$N$_4$ resonator

TL;DR

This study visualizes and analyzes the mechanical modes of a hybrid hBN/Si3N4 resonator, demonstrating mode hybridization and potential for engineering high-Q, low-mass resonators for optomechanics and sensing.

Contribution

It provides the first detailed imaging and characterization of hybrid mechanical modes in a 2D hBN and Si3N4 resonator, showing how hybridization affects mode properties.

Findings

Mode hybridization between hBN and Si3N4 resonator modes.

Resonance frequencies and spatial profiles match finite-element simulations.

Hybridization can significantly alter quality factors and motional mass.

Abstract

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 an 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.