Electronic properties of WS2 and WSe2 monolayers with biaxial strain: A first-principles study

Muoi, Do; Hieu, Nguyen N.; Phung, Huong Thi Thu; Phuc, Huynh V.; Amin, B.; Hoi, Bui D.; Hiếu, Nguyễn Văn; Nhan, Le C.; Nguyen, Chuong V.; Le, P.T.T.

doi:10.1016/j.chemphys.2018.12.004

Cited by 73 publications

(31 citation statements)

References 55 publications

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“…4(c). The parameter ∆, describing the orbital gap at K and K' valley, decreases as we increase the lattice constant in agreement with literature [48,54,[75][76][77][78]. Keeping the orbital decomposed band structure ( Fig.…”

Section: Geometry Band Structure and Fitted Resultssupporting

confidence: 89%

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

2019

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When considering transition-metal dichalcogenides (TMDCs) in van der Waals (vdW) heterostructures for periodic ab-initio calculations, usually, lattice mismatch is present, and the TMDC needs to be strained. In this study we provide a systematic assessment of biaxial strain effects on the orbital, spin-orbit, and optical properties of the monolayer TMDCs using ab-initio calculations. We complement our analysis with a minimal tight-binding Hamiltonian that captures the low-energy bands of the TMDCs around K and K' valleys. We find characteristic trends of the orbital and spinorbit parameters as a function of the biaxial strain. Specifically, the orbital gap decreases linearly, while the valence (conduction) band spin splitting increases (decreases) nonlinearly in magnitude when the lattice constant increases. Furthermore, employing the Bethe-Salpeter equation and the extracted parameters, we show the evolution of several exciton peaks, with biaxial strain, on different dielectric surroundings, which are particularly useful for interpreting experiments studying strain-tunable optical spectra of TMDCs.

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Section: Geometry Band Structure and Fitted Resultssupporting

confidence: 89%

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

2019

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“…In our DFT calculations, the decrease of bandgap and its transition from direct-to-indirect bandgap are similarly observed in Figure 5C. As for compressive strain (i.e., negative strain in Figure 5C), direct-to-indirect bandgap transition is observed at a strain of À1.5%, which is similar to previous reports with MoS 2 (Chang et al, 2013;Yun et al, 2012;Muoi et al, 2019). The bandgap changes and its direct-to-indirect transition could be explained by strain-induced modification of the coupling strength between atomic orbitals in TMDs.…”

Section: Resultssupporting

confidence: 89%

“…semiconducting TMDs such as 2H-WS 2 , which results in direct-indirect band gap transition (Yun et al, 2012;Wang et al, 2015;Shi et al, 2013;Chang et al, 2013;Desai et al, 2014;Johari and Shenoy, 2012;Peelaers and Van de Walle, 2012;Lu et al, 2012;Zhang et al, 2013;Maniadaki et al, 2016;Muoi et al, 2019). Accordingly, the growth mechanism in CVD remains to be further explored to understand and modulate the strain effects on the electronic properties of few-layered WS 2 .…”

Section: Open Accessmentioning

confidence: 99%

Bandgap modulation in the two-dimensional core-shell-structured monolayers of WS2

et al. 2022

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Tungsten disulfide (WS 2 ) has tunable bandgaps, which are required for diverse optoelectronic device applications. Here, we report the bandgap modulation in WS 2 monolayers with two-dimensional core-shell structures formed by unique growth mode in chemical vapor deposition (CVD). The core-shell structures in our CVD-grown WS 2 monolayers exhibit contrasts in optical images, Raman, and photoluminescence spectroscopy. The strain and doping effects in the WS 2 , introduced by two different growth processes, generate PL peaks at 1.83 eV (at the core domain) and 1.98 eV (at the shell domain), which is distinct from conventional WS 2 with a primary PL peak at 2.02 eV. Our density functional theory (DFT) calculations explain the modulation of the optical bandgap in our coreshell-structured WS 2 monolayers by the strain, accompanying a direct-to-indirect bandgap transition. Thus, the core-shell-structured WS 2 monolayers provide a practical method to fabricate lateral heterostructures with different optical bandgaps, which are required for optoelectronic applications.

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“…A new advantage in the nanoscale materials opened up a new window for twodimensional dichalcogenides (TMDCs). MX 2 such as MoS 2 , MoSe 2 [20], WS 2 and WSe 2 [21,22] has sizable bandgaps that change from indirect to direct in single layers, allowing applications such as transistors, photodetectors and electroluminescent devices. Transition metal dichalcogenide compounds also have a similar structure with graphite, which can be made by chemical vapor deposition such as MoS 2 [23]; in addition, the 2D MoS 2 sheets are made by micro-mechanical cleavage as old as grapheme [23].…”

Section: Introductionmentioning

confidence: 99%

Structural, electronic and optical properties of graphene-like nano-layers MoX2(X:S,Se,Te): DFT study

et al. 2019

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Using the first principle calculations, the structural, electronic and optical properties of the monolayer graphene-like MoX 2 sheet are calculated. Our results show that the chalcogenide atoms in the stability and the lattice parameters of the MoX 2 sheet have a key role, although it is known that the electronic properties are more dependent on the metal atoms in these sheets. Our data also confirm semiconductor behavior of the MoX 2 monolayers with direct band gap for S, Se and Te chalcogenides. Compared with the bulk compounds, they have similar structural properties but represent unique electronic and optical properties that can be used in nano-devices, nano-electronics and so on. In this work, the investigation of the chalcogenide atoms role in modifying the optical properties of these single-layer sheets, such as absorption and refraction coefficients, is carried out; the dielectric constant plays an important role. We also try to study the possibility of using these compounds on the solar energy industries and optical devices.

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Electronic properties of WS2 and WSe2 monolayers with biaxial strain: A first-principles study

Cited by 73 publications

References 55 publications

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

Strain-tunable orbital, spin-orbit, and optical properties of monolayer transition-metal dichalcogenides

Bandgap modulation in the two-dimensional core-shell-structured monolayers of WS2

Structural, electronic and optical properties of graphene-like nano-layers MoX2(X:S,Se,Te): DFT study

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