Beta-gallium oxide (β-Ga₂O₃), an emerging ultrawide bandgap (~4.8 eV) semiconductor, exhibits excellent electrical properties and cost advantages, being made as a promising candidate for high-power, high-frequency, and optoelectronic applications. Furthermore, its superior mechanical properties, including a Young’s modulus of 261 GPa, a mass density of 5950 kg/m³, and an acoustic velocity of 6623 m/s, make it particularly attractive for realizing high-frequency micro- and nanoelectromechanical system (M/NEMS) resonators. In this work, the energy dissipation mechanisms are investigated in two different β-Ga₂O₃ NEMS resonator geometries – doubly-clamped beams (10.5–20.8 μm length) and circular drumheads (3.3–5.3 μm diameter) – through theoretical analysis, finite element model (FEM) simulations, and experimental measurements under vacuum condition (<50 mTorr).

The dominant energy dissipation mechanisms in resonators are investigated, including Akhiezer damping (AKE), thermoelastic damping (TED), clamping loss, and surface loss, by using a combined theoretical and FEM approach. Experimentally, the resonators are made by employing mechanical exfoliation combined with dry transfer techniques, yielding device thickness of 30–500 nm as verified by atomic force microscopy (AFM). Subsequently, laser interferometry is used to characterize the resonator dynamics. The resonant frequency f is obtained in a range of 5–75 MHz and the quality factor Q is approximately 200–1700 obtained through Lorentzian fitting of the resonant spectra, thus verifying the theoretical and simulation results. Our analysis indicates that surface loss and clamping loss are the main limiting factors for the Q values of current β-Ga₂O₃ resonators. Conversely, AKE and TED are mainly affected by material properties and resonator geometry, thus setting an upper limit for the achievable Q values with f×Q product reaching up to 10¹⁴ Hz.

Our study provides a comprehensive framework integrating both theoretical analysis and experimental validation for understanding the complex energy dissipation mechanism inside a β-Ga₂O₃ NEMS resonator, and optimizes Q value through strain engineering and phonon crystal anchoring. These findings provide essential guidance for optimizing the performance and modulating the bandwidth of β-Ga₂O₃ NEMS resonator in high-frequency and high-power applications.