Abstract
The chemical vapor deposition (CVD)-grown two-dimensional molybdenum disulfide (MoS2) structures comprise of flakes of few layers with different dimensions. The top layers are relatively smaller in size than the bottom layers, resulting in the formation of edges/steps across adjacent layers. The strain response of such few-layer terraced structures is therefore likely to be different from exfoliated few-layered structures with similar dimensions without any terraces. In this study, the strain response of CVD-grown few-layered MoS2 terraced structures is investigated at the atomic scales using classic molecular dynamics (MD) simulations. MD simulations suggest that the strain relaxation of CVD-grown triangular terraced structures is observed in the vertical displacement of the atoms across the layers that results in the formation of Moiré patterns. The Moiré islands are observed to nucleate at the corners or edges of the few-layered structure and propagate inwards under both tensile and compressive strains. The nucleation of these islands is observed to happen at tensile strains of ~ 2% and at compressive strains of ~2.5%. The vertical displacements of the atoms and the dimensions of the Moiré islands predicted using the MD simulation are in excellent agreement with that observed experimentally.
Highlights
Two-dimensional (2D) transition metal dichalcogenide (TMD) structures, with their unique electronic structure, show significant promise for applications in field effect transistors[1], optoelectronic device[2], photo transistors and photo detectors[3]
These ripples are attributed to the presence of edges in chemical vapor deposition (CVD)-grown MoS2 structures that result in differences in the strains across the layers[24]
This study investigates the mechanisms of formation of Moiré patterns under applied strains in CVD-grown bilayer MoS2 structures using molecular dynamics (MD) simulations
Summary
Two-dimensional (2D) transition metal dichalcogenide (TMD) structures, with their unique electronic structure, show significant promise for applications in field effect transistors[1], optoelectronic device[2], photo transistors and photo detectors[3]. When bulk MoS2 is thinned to monolayer, the VBM shifts from Γ to K, and the CBM shifts from Σmin to K, which results in an intriguing indirect-to-direct transition of band gap energies for monolayer MoS2. A significant number of theoretical studies have been carried out to understand the variations in the electronic band structures of 2D MoS2 structures[18,19,20,21,22,23] These studies suggest a transition from a direct band gap to an indirect band gap for monolayer MoS2 at ~ 2% tensile strains and a semiconductor to metallic transition at ~10% biaxial strain[18]. The vertically heterogenous strain configurations across layers can induce/engender lattice mismatch between different layers, which results in a Moiré-like superstructure in individual layers, i.e., Moiré patterns[28]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
