Abstract
The potential of the applicability of two-dimensional molybdenum disulfide (MoS2) structures, in various electronics, optoelectronics, and flexible devices requires a fundamental understanding of the effects of strain on the electronic, magnetic and optical properties. Particularly important is the recent capability to grow large flakes of few-layered structures using chemical vapor deposition (CVD) wherein the top layers are relatively smaller in size than the bottom layers, resulting in the presence of edges/steps across adjacent layers. This paper investigates the strain response of such suspended few-layered structures at the atomic scales using classic molecular dynamics (MD) simulations. MD simulations suggest that the suspended CVD-grown structures are able to relax the applied in-plane strain through the nucleation of ripples under both tensile and compressive loading conditions. The presence of terraced edges in these structures is the cause for the nucleation of ripples at the edges that grow towards the center of the structure under applied in-plane strains. The peak amplitudes of ripples observed are in excellent agreement with the experimental observations. The study provides critical insights into the mechanisms of strain relaxation of suspended few-layered MoS2 structures that determine the interplay between the mechanical response and the electronic properties of CVD-grown structures.
Highlights
The 2-dimensional (2D) structures of MoS2 exhibit significantly different electronic band structure from bulk MoS2 structures[1,2] and show significant promise for applications in field effect transistors[3], optoelectronics[4], photo transistors and detectors[5], and chemical catalysts[6,7]
Ripples are observed near edge terminals in chemical vapor deposition (CVD)-grown MoS2 structures using scanning tunneling microscopy (STM)[34]
The current study investigates the effect of the size of the layers and mechanism of the strain relaxation of suspended CVD-grown multilayered MoS2 structures at the experimental length scales using classical molecular dynamics (MD) simulations
Summary
The 2-dimensional (2D) structures of MoS2 exhibit significantly different electronic band structure from bulk MoS2 structures[1,2] and show significant promise for applications in field effect transistors[3], optoelectronics[4], photo transistors and detectors[5], and chemical catalysts[6,7]. The capability to grow high quality and large areas of ML and FL MoS2 sheets for device applications has been made possible through chemical vapor deposition (CVD)[29,30,31]. These as-grown 2D terrace structures comprise of flakes of varying number of layers wherein the top layers are relatively smaller in size than the bottom www.nature.com/scientificreports/. Layers, resulting in the formation of terrace regions and edges/steps across adjacent layers The presence of these edges is likely to affect the observed strain-induced electronic and mechanical response of 2D MoS2 structures that do not include such edges. The DFT simulations focused on the strain response of bilayer structures, the effect of number of layers as well as the mechanism of strain relaxation at the atomic scale remain unknown
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