Exciton-dominant electroluminescence from a diode of monolayer MoS2

Ye, Yu; Ye, Ziliang; Gharghi, Majid; Zhu, Hanyu; Zhao, Mervin; Wang, Yuan; Yin, Xiaobo; Zhang, Xiang

doi:10.1063/1.4875959

Cited by 93 publications

(98 citation statements)

References 23 publications

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“…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] .…”

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confidence: 99%

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

Ross¹,

Rivera²,

Schaibley³

et al. 2017

Nano Lett.

281

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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mentioning

confidence: 99%

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

Ross¹,

Rivera²,

Schaibley³

et al. 2017

Nano Lett.

281

284

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“…The electroluminescence has been observed in two-dimensional monolayer field-effect transistors or p-n light-emitting diodes made of MoS 2 [9,10], WSe 2 [11], and WS 2 [12]. Single layer molybdenum disulfide (MoS 2 ) field-effect transistors can emit electroluminescence (visible light) at 1.8 eV thanks to its direct band gap [9].…”

Section: Light-emitting Diodesmentioning

confidence: 99%

“…Electrostatic gating must be used to improve control and efficiency of light emission. A light-emitting diode based on a two-dimensional monolayer MoS 2 deposited on a heavily p-type doped silicon substrate [10]. This device emits a high energy exciton peak in 2.255 eV through of a direct-exciton transition at room temperature which opened the possibility of controlling valley and spin excitation.…”

Section: Light-emitting Diodesmentioning

confidence: 99%

Graphene against Other Two-Dimensional Materials: A Comparative Study on the Basis of Photonic Applications

Vargas-Bernal¹

2017

Graphene Materials - Advanced Applications

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Two-dimensional materials represent the basis of technological development to produce applications with high added value for nanoelectronics, photonics, and optoelectronics. In first decades of this century, these materials are impelling this development through materials based on carbon, silicon, germanium, tin, phosphorus, arsenic, antimony, and boron. 2D materials for photonic applications used until now are graphene, silicene, germanene, stanene, phosphorene, arsenene, antimonene, and borophene. In this work, the main strategies to modify optical properties of 2D materials are studied for achieving photodetection, transportation, and emitting of light. Optical properties analyzed here are refractive index, extinction coefficient, relative permittivity, absorption coefficient, chromatic dispersion, group index, and transmittance. The transmittance spectra of various two-dimensional materials are presented here with the aim of classifying them from photonic point-of-view. A performance comparison between graphene and other twodimensional materials is done to help the designer choose the best design material for photonic applications. In next three decades, a lot of scientific research will be realized to completely exploit the use of 2D materials either as single monolayers or as stacked multilayers in several fields of knowledge with a special emphasis in the optoelectronics and photonic industry in benefit of the industry and ultimately to our society.

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“…In the single-layer limit, MoS 2 exhibits a direct band gap of 1.9 eV, 20,21 promising for light-emitting diodes. 22,23 In any applications using two-dimensional materials, the energy-band structure and the relative band alignments are crucial inputs for designing and understanding devices.In this work, we present a tunnel diode based on a combination of an MoS 2 gate with a Si FET. Using a n-typeMoS 2 /SiO 2 /p-type-Si heterostructure, we observe current characteristics with multiple negative differential resistance (NDR) peaks.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Observing the semiconducting band-gap alignment of MoS2 layers of different atomic thicknesses using a MoS2/SiO2/Si heterojunction tunnel diode

Nishiguchi

Castellanos-Gómez

Yamaguchi

et al. 2015

Applied Physics Letters

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We demonstrate a tunnel diode composed of a vertical MoS 2 /SiO 2 /Si heterostructure. A MoS 2 flake consisting four areas of different thicknesses functions as a gate terminal of a silicon field-effect transistor. A thin gate oxide allows tunneling current to flow between the n-type MoS 2 layers and p-type Si channel. The tunneling-current characteristics show multiple negative differential resistance features, which we interpret as an indication of different conduction-band alignments of the MoS 2 layers of different thicknesses. The presented tunnel device can be also used as a hybrid-heterostructure device combining the advantages of two-dimensional materials with those of silicon transistors. V C 2015 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4927529] Downsizing of Si field-effect transistors (FETs) has allowed ever-advancing performance and integration of electrical circuits. The downsizing also provides Si with unique characteristics including band-gap opening, 1,2 energy-level quantization, 3,4 and valley splitting, 5,6 which open ways for fascinating applications, e.g., a resonant tunneling diodes, 3 a light emitting diodes, 6,7 and a tool for tunneling spectroscopy. 4 In particular, tunneling spectroscopy, which is typically done using a scanning tunneling microscopy (STM), provides not only information about energy quantization, not observable in conventional current characteristics of FETs, but also can be used to implement light emitting devices. 8 These approaches promise for "More than Moore," which expands functions of Si FETs and their circuits. However, since Si has indirect band gap and heavy electron mass, applications utilizing band-diagram engineering have limitations compared to compound semiconductors. Two-dimensional materials, on the other hand, have recently emerged as a candidate to substitute Si in "Beyond CMOS." With direct bandgaps and lighter electron masses, two-dimensional materials have attracted much attention because of their potential for electronic and optical applications as well as physics. The research on the twodimensional materials had been boosted by the pioneering works on graphene 9,10 and has covered other materials including transition-metal dichalcogenides MX 2 and black phosphorous. 11-13 These two-dimensional materials are composed of layers with strong in-plane bonds and with weak van der Waals force mediated interlayer interactions, making possible to exfoliate them into atomically thin layers. MoS 2 , one of the layered MX 2 materials, has been studied widely for various applications such as transistors, 14,15 photo sensors, 16,17 and valleytronics and spintronics devices. 18,19 In analogy with other two-dimensional materials, the band gap of MoS 2 is modulated by the number of MoS 2 layers, showing an indirect band gap of 1.28 eV in bulk that increases while reducing the number of layers. In the single-layer limit, MoS 2 exhibits a direct band gap of 1.9 eV, 20,21 promising for light-emitting diodes. 22,23 In any applications using two-dimensional ma...

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Exciton-dominant electroluminescence from a diode of monolayer MoS2

Cited by 93 publications

References 23 publications

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

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

Graphene against Other Two-Dimensional Materials: A Comparative Study on the Basis of Photonic Applications

Observing the semiconducting band-gap alignment of MoS2 layers of different atomic thicknesses using a MoS2/SiO2/Si heterojunction tunnel diode

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