Strain engineering of WS2, WSe2, and WTe2

Amin, B.; Kaloni, Thaneshwor P.; Schwingenschlögl, Udo

doi:10.1039/c4ra06378c

Cited by 301 publications

(150 citation statements)

References 32 publications

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“…This finding agrees with the fact that the band splitting due to SOC is about 50 meV larger in bulk WeS 2 than in bulk WSe 2 . 27,28 For graphene sandwiched between WSe 2 layers, we find a similar band gap and under SOC an enhancement of the valence and conduction band splittings to 149 meV and 153 meV, respectively, compare TABLE I. Distance between the subsystems (d), binding energy per C atom (E b ), band gap (E g ), valence band splitting (D v ), and conduction band splitting (D c ).…”

Section: 2mentioning

confidence: 55%

Quantum spin Hall states in graphene interacting with WS2 or WSe2

Kaloni

Kou

Frauenheim

et al. 2014

Applied Physics Letters

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In the framework of first-principles calculations, we investigate the structural and electronic properties of graphene in contact with as well as sandwiched between WS 2 and WSe 2 monolayers.We report the modification of the band characteristics due to the interaction at the interface and demonstrate that the presence of the dichalcogenides results in quantum spin Hall states in the absence of a magnetic field.

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Section: 2mentioning

confidence: 55%

Quantum spin Hall states in graphene interacting with WS2 or WSe2

Kaloni

Kou

Frauenheim

et al. 2014

Applied Physics Letters

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“…The splitting of the energy bands near CBM and VBM is well known from previous studies and is attributed to a combination of spin-orbit splitting and interlayer interactions. 53,60 The electric field is similar to the strain engineering 35 which induces splits and shifts of the bands near the Fermi level due to an increasing/ decreasing coupling between the W and Se atoms.…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the explosive popularity of 2D nanomaterials does not only rely on the intrinsic material properties themselves, but highly depends on the tunable electronic properties. [5][6][7][8][24][25][26][27][28][29][30][31] Several strategies are commonly used: nanopatterning, 24-29 chemical treatment, 30,31 pressure, 32 strain engineering, [33][34][35] and the application of external electric fields. 1,[36][37][38][39][40][41][42][43][44][45][46][47] However, there are many drawbacks in the practical implementation of nanopatterning, chemical treatment, pressure, and strain engineering in 2D TMDs.…”

Section: Introductionmentioning

confidence: 99%

Bandstructure modulation of two-dimensional WSe2 by electric field

Dai

Wang

et al. 2015

Journal of Applied Physics

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By means of density functional theory computations, we study band-gap tuning in multi-layer WSe2 sheets by external electric fields. It shows that the fundamental band gap of WSe2 film continuously decreases with an increasing vertical electric field, eventually rendering them metallic. The critical electric fields, at which the semiconductor-to-metal transition occurs, are predicted to be in the range of 0.6–2 V/nm depending on the number of layers. This gap-tuning effect yields a robust relationship, which is essentially characterized by the giant Stark effect (GSE) coefficient S, for the rate of change of band gap with applied external field. The GSE coefficient S is proportional to the number of layers and it can be expressed as (n − 1)c/2.

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“…Recently, the impact of strain on optical and electronic properties of TMDs has gained importance, since these atomically thin materials are highly sensitive to deformations of their lattice structure, suggesting strain-induced tailoring of TMD characteristics. Recent experimental [5][6][7][8][9] and theoretical [9][10][11][12][13][14][15][16][17] studies have revealed that strain can significantly change the electronic band structure of TMDs. In particular, the direct band gap decreases (increases) for tensile (compressive) strain, resulting in a considerable redshift (blueshift) of optical resonance.…”

Section: Introductionmentioning

confidence: 99%

Impact of strain on the optical fingerprint of monolayer transition-metal dichalcogenides

et al. 2017

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Strain presents a straightforward tool to tune electronic properties of atomically thin nanomaterials that are highly sensitive to lattice deformations. While the influence of strain on the electronic band structure has been intensively studied, there are only a few works on its impact on optical properties of monolayer transition-metal dichalcogenides (TMDs). Combining microscopic theory based on Wannier and Bloch equations with nearest-neighbor tight-binding approximation, we present an analytical view on how uni-and biaxial strain influences the optical fingerprint of TMDs, including their excitonic binding energy, oscillator strength, optical selection rules, and the radiative broadening of excitonic resonances. We show that the impact of strain can be reduced to changes in the lattice structure (geometric effect) and in the orbital functions (overlap effect). In particular, we demonstrate that the valley-selective optical selection rule is softened in the case of uniaxial strain due to the introduced asymmetry in the lattice structure. Furthermore, we reveal a considerable increase of the radiative dephasing due to strain-induced changes in the optical matrix element and the excitonic wave functions.

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Strain engineering of WS₂, WSe₂, and WTe₂

Cited by 301 publications

References 32 publications

Quantum spin Hall states in graphene interacting with WS2 or WSe2

Quantum spin Hall states in graphene interacting with WS2 or WSe2

Bandstructure modulation of two-dimensional WSe2 by electric field

Impact of strain on the optical fingerprint of monolayer transition-metal dichalcogenides

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