Nanomechanical Strain Concentration on a Two-Dimensional Nanobridge within a Large Suspended Bilayer Graphene for Molecular Mass Detection

Abstract

The recent emergence of strain gradient engineering directly affects the nanomechanics, optoelectronics and thermal transport fields in 2D materials. More specifically, large suspended graphene under very high stress represents the quintessence for nanomechanical mass detection through unique molecular reactions. Different techniques have been used to induce strain in 2D materials, for instance by applying tip indentation, pressure or substrate bending on a graphene membrane. Nevertheless, an efficient way to control the strain of a structure is to engineer the system geometry as shown in everyday life in architecture and acoustics. Similarly, we studied the concentration of strain in artificial nanoconstrictions (~100 nm) in a suspended epitaxial bilayer graphene membrane with different geometries and lengths ranging from 10 to 40 µm. We carefully isolated the strain signature from µ-Raman measurements and extracted information on a scale below the laser spot size by analyzing the broadened shape of our Raman peaks, up to 100 cm -1 . We potentially measured a strong strain concentration in a nanoconstriction up to 5%, which is 20 times larger than the native epitaxial graphene strain. Moreover, with a bilayer graphene, our configuration naturally enhanced the native asymmetric strain between the upper and lower graphene layers. In contrast to previous results, we can achieve any kind of complex strain tensor in graphene thanks to our structural approach. This method completes the previous strain-induced techniques and opens up new perspectives for bilayer graphene and 2D heterostructures based devices.

Two-Dimensional Layered Materials Offering Expanded Applications in Flatland

“…Furthermore, scanning thermal microscopy measurements have demonstrated that graphene can also act as a thermally conducting coating on a variety of substrates such as SiO 2 , Al 2 O 3 , and poly­(ethylene terephthalate) . Graphene also has great potential for molecular mass detection using nanobridges of bilayer graphene, as well as for proton-selective transmission by sandwiching graphene between proton-exchange membranes . On the other hand, photodetectors made of graphene oxide–semiconductor junctions display high responsivities …”

“…The structures highlighted above were adapted from the publications in this virtual issue as follows: SnS, 17 GeS, 18 BP, 20 h-BN, 27 MoO 3 , 24 CPs, 38 HOFs, 40 MOCHAs, 41 MXenes, 44 and heterostructures 2D/2D, 49 1D/2D, 55 coating on a variety of substrates such as SiO 2 , Al 2 O 3 , and poly(ethylene terephthalate). 32 Graphene also has great potential for molecular mass detection using nanobridges of bilayer graphene, 33 as well as for proton-selective transmission by sandwiching graphene between proton-exchange membranes. 34 On the other hand, photodetectors made of graphene oxide−semiconductor junctions display high responsivities.…”

Effect of misfit strain on the buckling of graphene/MoS2 van der Waals heterostructures

“…The misfit strain in a heterostructure can be controlled in various ways, e.g. by appropriately choosing the substrate [29] and the structural design [30], or by photoelectrochemical etching process [31]. The misfit strain directly affects the physical and mechanical properties of a vdW heterostructure.…”

Misfit strain-induced energy dissipation for graphene/MoS2 heterostructure nanomechanical resonators

“…As a characteristic feature for the van der Waals heterostructure, there is an inevitable misfit strain between the constituting atomic layers, which can be caused by various reasons including the different lattice constants for these different atomic layers [21][22][23]. The strain in the atomic layers can be manipulated through various experimental techniques, including the substrate [24], the photoelectrochemical etching process [25], the structural design [26], and etc. Experiments have demonstrated the effect of the relative sliding of two graphene layers on the electrical properties of bilayer graphene [27,28].…”