Atomic layer MoS₂-graphene van der Waals heterostructure nanomechanical resonators

Abstract

Heterostructures play significant roles in modern semiconductor devices and micro/nanosystems in a plethora of applications in electronics, optoelectronics, and transducers. While state-of-the-art heterostructures often involve stacks of crystalline epi-layers each down to a few nanometers thick, the intriguing limit would be hetero-atomic-layer structures. Here we report the first experimental demonstration of freestanding van der Waals heterostructures and their functional nanomechanical devices. By stacking single-layer (1L) MoS on top of suspended single-, bi-, tri- and four-layer (1L to 4L) graphene sheets, we realize an array of MoS-graphene heterostructures with varying thickness and size. These heterostructures all exhibit robust nanomechanical resonances in the very high frequency (VHF) band (up to ∼100 MHz). We observe that fundamental-mode resonance frequencies of the heterostructure devices fall between the values of graphene and MoS devices. Quality (Q) factors of heterostructure resonators are lower than those of graphene but comparable to those of MoS devices, suggesting interface damping related to interlayer interactions in the van der Waals heterostructures. This study validates suspended atomic layer heterostructures as an effective device platform and provides opportunities for exploiting mechanically coupled effects and interlayer interactions in such devices.

Dynamically-enhanced strain in atomically thin resonators

“…ince the first demonstration of mechanical resonators made from suspended graphene layers 1 , considerable progress has been made to conceive nano-mechanical systems based on 2D materials 2,3 with well-characterised performances [4][5][6][7][8] , for applications in mass and force sensing 9 but also for studies of heat transport 10,11 , non-linear mode coupling [12][13][14] and optomechanical interactions 5,15,16 . These efforts triggered the study of 2D resonators beyond graphene, made for instance from transition metal dichalcogenide layers 8,11,17,18 and van der Waals heterostructures [19][20][21] . In suspended atomically thin membranes, a moderate out-of-plane stress gives rise to large and swiftly tunable strains, in excess of 1% 22,23 , opening numerous possibilities for strain-engineering 24 .…”

Perspectives on smart stents with sensors: From conventional permanent to novel bioabsorbable smart stent technologies

“…(b) In-stent restenosis develops with the re-occurrence of fatty deposition (as shown in yellow) in the stenotic region. (c) After stent is implanted, delayed endothelialization or endothelial denudation leads to the migration of smooth muscle cells from the middle layer of blood vessel leading to smooth muscle cell proliferation and neointimal hyperplasia Musick, Coffey, and Irazoqui (2010) (Munawar et al, 2019;Ye, Lee, & Feng, 2017), mass analysis in the range of mega-to gigadalton range including that of most viruses and disease biomarkers is possible (Dominguez-Medina et al, 2018;Gil-Santos et al, 2010). In nanoscale, the response of such nanoresonators depends not only on the mass of the adsorbed cells but also on the mechanical properties of those cells (Ramos, Tamayo, Mertens, Calleja, & Zaballos, 2006).…”

“…Even though hailed as the future of coronary stenting, bioresorbable stents have not yet attained the expected clinical efficacy.The rapid advancements in the field of bioresorbable electronic materials(Cha et al, 2019;Chen & Ahn, 2020;Kang, Koo, Lee, & Rogers, 2018) can be incorporated to bioabsorbable stent systems to develop novel bioabsorbable smart stents. In spite of its biological advantage, bioresorbable electronic systems can mitigate the problems associated with ever-growing electronic waste posing hazardous environmental impacts(Ye et al, 2017). One of the challenges associated with bioresorbable sensors for clinical applications inside human body is the inability to sustain consistent sensing function in biofluids throughout the intended scaffolding period before undergoing complete resorption(Shin et al, 2019).Biodegradable poly-L-lactide (PLLA)-based piezoelectric force sensors, which were developed for measuring bio-physiological pressures, exhibited precise measurements in a wide range of 0-18 kPa (Curry et al, 2018).…”

High‐Speed Quantum Transducer with a Single‐Photon Emitter in a 2D Resonator

“…Similar heterostructure 2D resonators have been demonstrated at room temperature already. [ 52 ] Their quality factor will be much higher at low temperatures.…”