Hexagonal boron nitride (h-BN) nanomechanical resonators with temperature-dependent multimode operations

We present the first experimental demonstrations of ultrathin hexagonal boron nitride (h-BN) circular drumhead vibrating resonators with multiple modes, operating in a wide temperature range from -7°C to 141°C, by characterizing flexural-mode resonances of the devices. We fabricate h-BN resonators with down to 10nm-thick h-BN crystalline flakes using a wet-chemistry-free, all-dry transfer technique. We observe distinct multimode resonances up to 5 modes, and resonance frequencies up to ~70MHz. In addition to spatial mapping of multimode thermomechanical motions, we observe very large temperature coefficients of frequency (TCfs) in these h-BN resonators, up to -2850ppm/K.