Determination of band alignment in the single-layer MoS2/WSe2 heterojunction

Chiu, Ming Hui; Zhang, Chengfei; Shiu, Hung-Wei; Chuu, Chih‐Piao; Chen, Chang-Hsiao; Chang, Chih Yuan S.; Chen, Chia Hao; Chou, M. Y.; Shih, Chih Kang; Li, Lain‐Jong

doi:10.1038/ncomms8666

Cited by 566 publications

(371 citation statements)

References 33 publications

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“…The valence band maximum (VBM) of MoS 2 has been reported at around −1.8 V, 22,33 and a substantially shorter tip-sample distance is thought to lead to the apparent difference in the measurements presented here. 31 Qualitatively, we can observe that the peaks appear inside the range normally considered to represent the band gap.…”

Section: Resultsmentioning

confidence: 80%

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Butler

Huang

et al. 2017

npj 2D Mater Appl

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This report presents a series of low-temperature (4.5 K) scanning tunneling microscopy and spectroscopy experimental results on monolayer MoS 2 deposited on highly oriented pyrolytic graphite using chemical vapor deposition. To reveal the detailed connection between atomic morphology and conductivity in twisted MoS 2 /graphite heterojunctions, we employ high-sensitivity tunneling spectroscopy measurements by choosing a reduced tip-sample distance. We discern previously unobserved conductance peaks within the band gap range of MoS 2 , and by comparing the tunneling spectra from MoS 2 grains of varying rotation with respect to the substrate, show that these features have small but non-negligible dependence on the moiré superstructure. Furthermore, within a single moiré supercell, atomically resolved tunneling spectroscopy measurements show that the spectra between the moiré high and low areas are also distinct. These in-gap states are shown to have an energy shift attributed to their local lattice strain, matching corresponding behavior of the conduction band edge, and we therefore infer that these features are intrinsic to the density of states, rather than experimental artifacts, and attribute them to the twisted stacking and local strain energy of the MoS 2 /graphite heterointerface.

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Section: Resultsmentioning

confidence: 80%

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Butler

Huang

et al. 2017

npj 2D Mater Appl

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“…Van der Waals (vdW) heterostructures composed of 2D layered materials have been attempted intensively recently due to the novel physical properties covering a wide range of electronic, optical, and optoelectronic systems 198, 199, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209, 210, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230, 231, 232, 233, 234, 235, 236, 237, 238, 239, 240, 241, 242. Jo and co‐workers130 synthesized polymorphic 2D tin‐sulfides of either p‐type SnS or n‐type SnS 2 via adjusting hydrogen during the process.…”

Section: Preparation Methods and Characterizationsmentioning

confidence: 99%

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

et al. 2016

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As an important component of 2D layered materials (2DLMs), the 2D group IV metal chalcogenides (GIVMCs) have drawn much attention recently due to their earth‐abundant, low‐cost, and environmentally friendly characteristics, thus catering well to the sustainable electronics and optoelectronics applications. In this instructive review, the booming research advancements of 2D GIVMCs in the last few years have been presented. First, the unique crystal and electronic structures are introduced, suggesting novel physical properties. Then the various methods adopted for synthesis of 2D GIVMCs are summarized such as mechanical exfoliation, solvothermal method, and vapor deposition. Furthermore, the review focuses on the applications in field effect transistors and photodetectors based on 2D GIVMCs, and extends to flexible devices. Additionally, the 2D GIVMCs based ternary alloys and heterostructures have also been presented, as well as the applications in electronics and optoelectronics. Finally, the conclusion and outlook have also been presented in the end of the review.

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“…Vertically stacking two different TMDs forms a new type of optically active heterojunction with type-II band alignment [23][24][25][26] . This results in a builtin vertical p-n junction 6,27,28 at the atomic scale and causes optically excited electrons and holes to be subsequently separated into opposite layers 29,30 .…”

Section: Main Textmentioning

confidence: 99%

Interlayer Exciton Optoelectronics in a 2D Heterostructure p–n Junction

Ross¹,

Rivera²,

Schaibley³

et al. 2017

Nano Lett.

290

284

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Semiconductor heterostructures are backbones for solid state based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures has enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb-bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe2-WSe2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p-n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the direct observation of resonant optical excitation of the interlayer exciton. The resulting photocurrent amplitude from the interlayer exciton is about 200 times smaller compared to the resonant excitation of intralayer exciton. This implies that the interlayer exciton oscillator strength is two orders of magnitude smaller than that of the intralayer exciton due to the spatial separation of electron and hole to opposite layers. These results lay the foundation for exploiting the interlayer exciton in future 2D heterostructure optoelectronic devices.Keywords: van der Waals heterostructure, optoelectronics, interlayer exciton, transition metal dichalcogenides, p-n junction. MAIN TEXTThe diverse family of van der Waals materials offers a platform for building heterojunctions with designer functionalities at the atomically thin limit 1,2 . Two-dimensional (2D) materials with metallic (graphene), semiconducting (group VIB transition metal dichalcogenides), and insulating (boron nitride, hBN) properties can be stacked into arbitrarily complex heterostructures (HSs). This has led to exciting progress both in science, such as the artificial superlattice yielding Hofstadter's butterfly [3][4][5] , and bandgap engineered devices, in particular efficient light emitting diodes and photodetectors 6,7 .In individual layers of transition metal dichalcogenides (TMDs) the direct bandgap 8,9 enables diverse applications in photovoltaics and light emitting devices (LEDs) [10][11][12][13][14][15][16] , while the valleycontrasting physics and resultant optical selection rules 17-21 suggests a new paradigm of optoelectronics utilizing the valley pseudospin 22 . Vertically stacking two different TMDs forms a new type of optically active heterojunction with type-II band alignment [23][24][25][26] . This results in a builtin vertical p-n junction 6,27,28 at the atomic scale and causes optically excited electrons and holes to be subsequently separated into opposite layers 29,30 . Due to the small interlayer separation, the spatial...

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Determination of band alignment in the single-layer MoS2/WSe2 heterojunction

Cited by 566 publications

References 33 publications

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Moiré-related in-gap states in a twisted MoS2/graphite heterojunction

Booming Development of Group IV–VI Semiconductors: Fresh Blood of 2D Family

Interlayer Exciton Optoelectronics in a 2D Heterostructure p–n Junction

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