Elastic Properties of Chemical-Vapor-Deposited Monolayer MoS₂, WS₂, and Their Bilayer Heterostructures

Abstract

Elastic properties of materials are an important factor in their integration in applications. Chemical vapor deposited (CVD) monolayer semiconductors are proposed as key components in industrial-scale flexible devices and building blocks of two-dimensional (2D) van der Waals heterostructures. However, their mechanical and elastic properties have not been fully characterized. Here we report high 2D elastic moduli of CVD monolayer MoS2 and WS2 (∼170 N/m), which is very close to the value of exfoliated MoS2 monolayers and almost half the value of the strongest material, graphene. The 2D moduli of their bilayer heterostructures are lower than the sum of 2D modulus of each layer but comparable to the corresponding bilayer homostructure, implying similar interactions between the hetero monolayers as between homo monolayers. These results not only provide deep insight into understanding interlayer interactions in 2D van der Waals structures but also potentially allow engineering of their elastic properties as desired.

Electronic structures and elastic properties of monolayer and bilayer transition metal dichalcogenides MX 2 ( M = Mo, W; X = O, S, Se, Te): A comparative first-principles study

“…The weakening binding between the metal and the chalcogen atom thus leads to the smaller Young modulus. In addition, we can also find that the Young modulus for those monolayer TMDCs with theoretical studies [13,14] and experiment measurement (180 ± 60 Nm −1 [9] or around 170 Nm −1 [10] ). We can also find that LDA calculations gave the closest results to experiment among three functionals, which suggest that LDA calculations are more accurate to describe the elastic property of monolayer TMDCs.…”

“…A high 2D elastic moduli of CVD monolayer MoS 2 and WS 2 (∼ 170 Nm −1 ) are also found. The 2D moduli of their bilayer heterostructures are found to be lower than the sum of 2D modulus for each layer, which shows a strong mechanical interlayer coupling between the layers [10] .…”

“…and their Bilayer Heterostructures are also investigated [10] . A high 2D elastic moduli of CVD monolayer MoS 2 and WS 2 (∼ 170 Nm −1 ) are also found.…”

Graphene versus MoS2: A short review

“…For SLMoS 2 , similar nanoindentation experiments obtained an average value for the effective Young's modulus of 180 ± 60 N·m −1 in the experiment by Bertolazzi et al [62], and 120 ± [64]. The nanoindentation set up has also been used to study the Young's modulus of thicker MoS 2 films [65].…”

Newborn 2D materials for flexible energy conversion and storage

“…Meanwhile, larger interlayer spacing, high theoretical specific capacity and power density make them very suitable in stretchable energy storage devices [16,17]. Induced by their excellent mechanical properties [18,19], the NB2DMs have been investigated in several flexible applications, such as batteries [20], SCs [21], photodetectors [22], etc.…”