Engineering Dissipation Dynamics for Enhanced Q Factor

Overview

Mechanical resonators can be thought of as tiny clocks and amplifiers for motion, and their quality factor (Q) determines how long a vibration persists before dissipation erases it. Our goal is to engineer Q in resonant MEMS and NEMS by identifying the dominant loss mechanisms and then reducing, redirecting, or actively controlling them so that the same device becomes quieter, more stable, and more sensitive. In current practice, Q is often improved by vacuum packaging, low loss materials, and careful geometry, yet performance still hits limits from energy leakage into supports (clamping or anchor loss), surface related dissipation, and, in ultrathin 2D devices, adsorption, air damping, and nonlinear damping. We go beyond passive optimization by combining mechanism level dissipation studies with active and structural Q control, including feedback based self sustaining oscillators and parametric pumping for linewidth and noise control, and stress engineering, trampoline style geometries, and phononic concepts that suppress leakage into supports. This approach works because we pair nanofabrication with precision measurement and multiscale modeling across multiple platforms, which lets us build loss budgets and apply targeted design rules instead of trial and error. The payoff is higher performance resonators for ultrasensitive sensing, timing and frequency references, compact RF signal processing, and hybrid classical and quantum transduction where controlled dissipation is essential.

Featured Publications:

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

We demonstrated graphene nanomechanical trampoline resonators that offer very high Q at room temperature with broad dynamic ranges. A 6 tether trampoline design reaches f times Q products up to 4.1 times 10^11 Hz among 2D resonators. This work highlights geometry enabled reduction of loss and routes to high performance 2D resonant transducers.

Thermal Piezoresistive Pumping on Double SiC Layer Resonator for Effective Quality Factor Tuning

We introduced thermal piezoresistive pumping in a double SiC layer bridge resonator to actively tune effective Q. The device leverages piezoresistive coupling to feed mechanical vibration from a DC bias, yielding up to 15.5 percent enhancement in effective Q from 12,200 to 14,100, with a pumping threshold reached near 0.18 W.

Nonlinear Stiffness and Nonlinear Damping in Atomically Thin MoS2 Nanomechanical Resonators

We reported quantitative measurements of nonlinear damping and nonlinear stiffness in single layer and few layer MoS2 resonators, including higher order damping and frequency detuning effects. This work establishes nonlinear dissipation as a critical design constraint for high drive operation, parametric control, and low noise 2D resonant transducers.

Temperature Compensated Graphene Nanomechanical Resonators

We demonstrated temperature compensated bilayer graphene resonators operating from 300 to 480 K. By engineering the device and clamp response, we achieved linear temperature coefficients of frequency on the order of minus 39 and minus 84 ppm per K, enabling improved frequency stability for sensing and reference applications.

High Quality Factors in Superlattice Ferroelectric Hf0.5Zr0.5O2 Nanoelectromechanical Resonators

We demonstrated integrated high Q ferroelectric NEMS resonators based on atomic layered hafnia zirconia superlattices. The devices reach quality factors up to 171,000 and frequency quality factor products above 10^11 Hz at room temperature in vacuum. The analysis points to clamping loss and surface loss as key limiting mechanisms and outlines directions to push f times Q further.

Single Crystal Silicon Thermal Piezoresistive Resonators as High Stability Frequency References

We reported single crystal silicon thermal piezoresistive resonators achieving about 0.2 ppb level frequency stability. With DC power feedback, the Allan deviation reaches about 0.236 ppb at an averaging time near 1.2 s, supporting integrated strategies for resonant frequency references.

References:

Huang XMH, Feng XL, Prakash MK, Kumar S, Zorman CA, Mehregany M, Roukes ML, “Fabrication of Suspended Nanomechanical Structures from Bulk 6H-SiC Substrates”, Materials Science Forum 457-460, 1531-1534 (2004). [This is the Proceedings of The 2004 International Conference on Silicon Carbide and Related Materials (ICSCRM 2003), Lyon, France, October 5-10 (2003)]. DOI: https://doi.org/10.4028/www.scientific.net/MSF.457-460.1531
Feng XL, Zorman CA, Mehregany M, Roukes ML, “Dissipation in Single-Crystal 3C-SiC UHF Nanomechanical Resonators”, Digest of Technical Papers, The 12^th Solid-State Sensors, Actuators, and Microsystems Workshop (Hilton Head’06), 86-89, Hilton Head Island, SC, June 4-8 (2006). (+talk, selection rate 8.9%). DOI: https://doi.org/10.48550/arXiv.cond-mat/0606711
Feng XL, He RR, Yang PD, Roukes ML, “Phase Noise and Frequency Stability of Very-High Frequency Silicon Nanowire Nanomechanical Resonators”, Digest of Technical Papers, The 14^th International Conference on Solid-State Sensors, Actuators, and Microsystems (Transducers’07), 327-330, Lyon, France, June 10-14 (2007). (+talk, selection rate 13.5%). DOI: https://doi.org/10.1109/SENSOR.2007.4300134
Lee J, Zhao L, Chiu HY, Shan J, Feng PXL^*, “Temperature Compensation of Graphene Nanomechanical Resonators”, Advanced Functional Materials 35, 2415708 (2025). DOI: https://doi.org/10.1002/adfm.202415708
[Frontispiece Article] Yousuf SMEH, Wang Y, Rudawski NG, Feng PXL^*, “Graphene Trampoline Nanomechanical Resonators with Very High Quality Factors and Broad Dynamic Ranges”, Advanced Functional Materials 35, e11158 (2025). DOI: https://doi.org/10.1002/adfm.202511158.
Guzman P, Dinh T, Qamar A, Lee J, Zheng XQ, Feng PXL, Rais-Zadeh M, Phan HP, Nguyen T, Foisal ARM, Li H, Nguyen NT, Dao DV, “Thermal-Piezoresistive Pumping on Double SiC Layer Resonator for Effective Quality Factor Tuning”, Sensors and Actuators A: Physical 343, 113678 (2022). DOI: https://doi.org/10.1016/j.sna.2022.113678
Zheng XQ, Tharpe T, Yousuf SMEH, Feng PXL, Tabrizian R^*, “High Quality Factors in Superlattice Ferroelectric Hf_0.5Zr_0.5O₂ Nanoelectromechanical Resonators”, ACS Applied Materials & Interfaces 14, 36807-36814 (2022). DOI: https://doi.org/10.1021/acsami.2c08414
Kaisar T, Lee J, Li D, Shaw SW, Feng PXL^*, “Nonlinear Stiffness and Nonlinear Damping in Atomically Thin MoS₂ Nanomechanical Resonators”, Nano Letters 22, 9831-9838 (2022). DOI: https://doi.org/10.1021/acs.nanolett.2c02629
Watkins CA, Lee J, McCandless JP, Hall HJ, Feng PXL^*, “Single-Crystal Silicon Thermal-Piezoresistive Resonators as High-Stability Frequency References”, Journal of Microelectromechanical Systems 34, 15-23 (2025). DOI: https://doi.org/10.1109/JMEMS.2024.3515098
Liu Y, Sun W, Abiri H, Feng PXL^*, Li Q, “Ultracompact 4H-Silicon Carbide Optomechanical Resonator with f_mQ_m Exceeding 10¹³ Hz”, Photonics Research 13, 2531-2538 (2025). DOI: https://doi.org/10.1364/PRJ.567674.