Tuning the electronic structure of monolayer graphene/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Mo</mml:mi><mml:msub><mml:mi mathvariant="normal">S</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>van der Waals heterostructures via interlayer twist

Jin, Wencan; Yeh, Ping-Cheng; Zaki, Nader; Chenet, Daniel; Arefe, Ghidewon; Hao, Yufeng; Sala, Alessandro; Menteş, Tevfik Onur; Dadap, Jerry I.; Locatelli, Andrea; Hone, James; Osgood, Richard M.

doi:10.1103/physrevb.92.201409

Cited by 58 publications

(36 citation statements)

References 40 publications

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“…This is also consistent with the findings of W. S. Yun et al [49] who showed, using the first-principles calculations, that the tensile strain reduces the gap energy. Furthermore, W. Jin [8] used microprobe angle resolved photoemission spectroscopy to prove the dependency of MoS 2 on the twist angle in graphene/MoS 2 heterostructure. They affirm that the band structure of MoS 2 becomes indirect except for 30 twist angle with respect to graphene, meanwhile graphene properties remain intact.…”

Section: Resultsmentioning

confidence: 99%

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

Aziza

Henck

Felice

et al. 2016

Carbon

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a b s t r a c tAtomically thin MoS 2 /graphene vertical heterostructures are promising candidates for nanoelectronic and optoelectronic technologies. In this work, we studied the optical and electronic properties of n doped single layer MoS 2 on p doped bilayer graphene vdW heterostructures. We demonstrate a non-uniform strain between two different orientation angles of MoS 2 monolayer on top of epitaxial bilayer graphene. A significant downshift of the E 1 2g mode, a slight downshift of the A 1g mode, and photoluminescence shift and quenching are observed between two MoS 2 monolayers differently oriented with respect to graphene; This could be mostly attributed to the strain-induced transition from direct to indirect bandgap in monolayer MoS 2 . Moreover, our theoretical calculations about differently-strained MoS 2 monolayers are in a perfect accordance with the experimentally observed behavior of differently-oriented MoS 2 flakes on epitaxial bilayer graphene. Hence, our results show that straininduced bandgap engineering of single layered MoS 2 is dependent on the orientation angle between stacked layers. These findings could be an interesting novel way to take advantage of the possibilities of MoS 2 and deeply exploit the capabilities of MoS 2 /graphene van der Waals heterostructures.© 2016 Elsevier Ltd. All rights reserved.Ever since the technique to isolate stable single-layer graphene was reported, the study of two-dimensional (2D) materials has gained a lot of research interest. Hence, a broad family of 2D materials like graphene, transition metal dichalcogenides (TMDCs), and topological insulators have been explored so far [1]. For the sake of exploring their fundamental interfacial interactions and conceiving novel electronic functionalities, vertical heterostructures composed of 2D materials stacked together by van der Waals (vdW) forces have attracted a great attention lately [2]. Among these combined structures, the MoS 2 /graphene heterostructure, among other heterostructures combining graphene with different layered 2D materials [3], shows a promising potential for next generation nanoelectronic and optoelectronic devices thanks to the outstanding carrier mobilities on one hand and the excellent optical responsivities on the other hand [4e6].However, research work about the structural quality, the band alignment and the optical emission properties of MoS 2 /graphene or graphene/MoS 2 vdW heterostructures are still limited. The exploration of such characteristic properties are fundamental to make possible the assembling of MoS 2 with graphene, pave the way for the realization of a well-ordered MoS 2 /graphene structure, and enable opportunities for a wide spectrum of optoelectronic functionalities. Inspirations of this present work arise from the fact that some of the theoretical calculations have predicted the crossover between a direct and indirect bandgap of MoS 2 originating from the modification of interlayer orientation [7e9]. Since the properties of MoS 2 /graphene heterostructure depend st...

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Section: Resultsmentioning

confidence: 99%

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

Aziza

Henck

Felice

et al. 2016

Carbon

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“…This valence-band compression can be attributed to the presence of the sapphire substrate since this has not been observed for the free-standing MoS 2 . The substrate likely induced a weak interaction with the bottom layer of S possibly leading to substrate-induced corrugations, Mo-S bond length variations, or changes in the dielectric environment as similarly suggested for MoS 2 on Si (111) [8,25]. The detailed modeling of the van der Waals interaction between MoS 2 and c sapphire and the resulting interfacial state is out of the scope of the current Rapid Communication as the realistic predictions of the band structure require computationally challenging techniques [26].…”

mentioning

confidence: 79%

“…The electronic states at the K point derive from in-plane Mo d(x 2 − y 2 )/d xy orbitals and therefore, only a significant in-plane strain is expected to affect the derived value of the effective mass. This is not the case here because no significant strain was observed and the c-sapphire substrate does not have a significant density of states near the VBM of MoS 2 unlike the MoS 2 /graphene system where charge-transfer-induced strain for certain twist angles can change the positions of band maxima [25]. Moreover, the overlap between the electronic states of misaligned grains, which comprise less than 10% of the grains, might have contributed to the broadening of the dispersion relationship which increased the uncertainty in the extracted values of the effective mass.…”

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confidence: 92%

Free-standing electronic character of monolayerMoS2in van der Waals epitaxy

et al. 2016

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We have evaluated as-grown MoS 2 crystals, epitaxially grown on a monocrystalline sapphire by chemical vapor deposition (CVD), with direct electronic band-structure measurements by energy-filtered k-space photoelectron emission microscopy performed with a conventional laboratory vacuum ultraviolet He I light source under off-normal illumination. The valence states of the epitaxial MoS 2 were mapped in momentum space down to 7 eV below the Fermi level. Despite the high nucleation density within the imaged area, the CVD MoS 2 possesses an electronic structure similar to the free-standing monolayer MoS 2 single crystal, and it exhibits hole effective masses of 2.41 ± 0.05 m 0 , and 0.81 ± 0.05 m 0 , respectively, at and K high-symmetry points that are consistent with the van der Waals epitaxial growth mechanism. This demonstrates the excellent ability of the MoS 2 CVD on sapphire to yield a highly aligned growth of well-stitched grains through epitaxial registry with a strongly preferred crystallographic orientation.

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“…The results obtained using time-and angle-resolved photoemission (ARPES) reveal a significant (~400 meV) reduction of the band gap of the MoS 2 layer induced by optical excitation [89]. The band gap and photoluminescence shift were reported to depend on the orientation of the graphene and MoS 2 monolayers [90,91]. The changes in electronic structure of graphene caused by interaction with MoS 2 monolayer were suggested to be less pronounced.…”

Section: Band Gap and Screening In Mos 2 Layersmentioning

confidence: 97%

“…A number of recent papers was devoted to detailed studies of a model 2D heterostructure formed of a single layer of MoS 2 on graphene [88][89][90][91][92][93]. It was found that the electronic structure of two-dimensional (2D) semiconductors can be significantly altered by screening effects.…”

Section: Band Gap and Screening In Mos 2 Layersmentioning

confidence: 99%

Dirac Cones in Graphene, Interlayer Interaction in Layered Materials, and the Band Gap in MoS2

Yakovkin

2016

Crystals

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Abstract:The 2D outlook of graphene and similar layers has initiated a number of theoretical considerations of electronic structure that are both interesting and exciting, but applying these ideas to real layered systems, in terms of a model 2D system, must be done with extreme care. In the present review, we will discuss the applicability of the 2D concept with examples of peculiarities of electronic structures and interactions in particular layered systems: (i) Dirac points and cones in graphene; (ii) van der Waals interaction between MoS 2 monolayers; and (iii) the issue of a 2D screening in estimates of the band gap for MoS 2 monolayers.

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Tuning the electronic structure of monolayer graphene/MoS2van der Waals heterostructures via interlayer twist

Cited by 58 publications

References 40 publications

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

Bandgap inhomogeneity of MoS2 monolayer on epitaxial graphene bilayer in van der Waals p-n junction

Free-standing electronic character of monolayerMoS2in van der Waals epitaxy

Dirac Cones in Graphene, Interlayer Interaction in Layered Materials, and the Band Gap in MoS2

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