Graphene Trampoline Nanomechanical Resonators with Very High Quality Factors and Broad Dynamic Ranges

Attaining high quality ( Q ) factors is desirable for appealing two‐dimensional (2D) materials‐enabled resonant optomechanical and electromechanical systems to fulfill their potential in energy‐efficient information transduction and sensing. Yet nanomechanical resonators in 2D materials often possess limited Q s without dissipation control. This study reports on the geometric design, fabrication, and measurements of 4‐ and 6‐tether trampoline resonators tailored from few‐layer and multilayer graphene, achieving the highest Q factors and f × Q products in 2D nanomechanical resonators at room temperature. High‐precision optical interferometric measurements enable characterization of the nanomechanical motions in the very high frequency band up to ≈70 MHz. Driven responses using opto‐thermal‐mechanical excitation in 4‐tether trampoline resonators reveal the fundamental mode Q reaching 9.1 × 10 3 . The 6‐tether trampoline demonstrates multimode resonances with remarkable Q s of 1.5 × 10 4 , 9.5 × 10 3 , and 4.8 × 10 3 at 23.47, 43.54, and 67.25 MHz, respectively, yielding the highest f × Q products (up to 4.1 × 10 11 Hz) among all 2D nanomechanical resonators reported. Furthermore, nonlinear Duffing responses of the trampolines are investigated, demonstrating broad dynamic ranges up to 72 dB. This study opens a pathway toward engineering very‐high‐ Q 2D nanomechanical resonators with enhanced performance for ultracoherent signal transduction and resonant sensing.