Abstract
Free standing, atomically thin transition metal dichalcogenides are a new class of ultralightweight nanoelectromechanical systems with potentially game-changing electro- and opto-mechanical properties, however, the energy dissipation pathways that fundamentally limit the performance of these systems is still poorly understood. Here, we identify the dominant energy dissipation pathways in few-layer MoS2 nanoelectromechanical systems. The low temperature quality factors and resonant frequencies are shown to significantly decrease upon heating to 293 K, and we find the temperature dependence of the energy dissipation can be explained when accounting for both intrinsic and extrinsic damping sources. A transition in the dominant dissipation pathways occurs at T ~ 110 K with relatively larger contributions from phonon-phonon and electrostatic interactions for T > 110 K and larger contributions from clamping losses for T < 110 K. We further demonstrate a room temperature thermomechanical-noise-limited force sensitivity of ~8 fN/Hz1/2 that, despite multiple dissipation pathways, remains effectively constant over the course of more than four years. Our results provide insight into the mechanisms limiting the performance of nanoelectromechanical systems derived from few-layer materials, which is vital to the development of next-generation force and mass sensors.
Highlights
Nanoelectromechanical systems (NEMS) derived from stable, atomically thin and ultralightweight two-dimensional (2D) materials like graphene[1,2,3], the transition metal dichalcogenides (TMDs)[4, 5], and phosphorene[6] offer the prospect of coupling the mechanical degree of freedom to the unique properties of each material[7] creating a new class of mechanically active architectures with novel electro- and opto-mechanical capabilities
Despite the presence of multiple dissipation pathways, measurements of the room temperature product Qω result in a force sensitivity of ~8 fN/Hz1/2 that is found to remain constant over the course of over four years, suggesting long-term durability and functionality of these few layer TMD NEMS
Few-layer MoS2 flakes were mechanically exfoliated from bulk MoS2 crystals onto a SiO2/(doped) Si substrate with predefined circular trenches etched out of the SiO2
Summary
Atomically thin transition metal dichalcogenides are a new class of ultralightweight nanoelectromechanical systems with potentially game-changing electro- and opto-mechanical properties, the energy dissipation pathways that fundamentally limit the performance of these systems is still poorly understood. We use an all-optical setup to characterize the T dependence of Q−1 for few-layer MoS2 NEMS, which allows us to determine the dissipation mechanisms responsible for the experimentally observed Q values from T = 4.4 K up to room temperature. The experimentally determined functional form of Q−1(T) indicates a transition in the dominant energy dissipation pathways at T ~ 110 K with relatively larger contributions to Q−1(T) from phonon-phonon and electrostatic interactions in the high temperature regime and larger contributions from clamping losses in the low temperature regime. Despite the presence of multiple dissipation pathways, measurements of the room temperature product Qω result in a force sensitivity of ~8 fN/Hz1/2 that is found to remain constant over the course of over four years, suggesting long-term durability and functionality of these few layer TMD NEMS
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