Optoelectronic crystal of artificial atoms in strain-textured molybdenum disulphide

Li, Hong; Contryman, Alex W.; Qian, Xiaofeng; Ardakani, Sina Moeini; Gong, Yongji; Wang, Xingli; Weisse, Jeffrey M.; Lee, Chi Hwan; Zhao, Jiheng; Ajayan, Pulickel M.; Li, Ju; Manoharan, Hari C.; Zheng, Xiaolin

doi:10.1038/ncomms8381

Cited by 382 publications

(473 citation statements)

References 36 publications

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“…4(c) measured, using a laser spot whose diameter is about 1 mm, in the centers of the small and big MoS 2 flakes (red and blue curves, respectively), we can obviously see that both peaks corresponding to the big flake are red-shifted. These downshifts can be explained based on the difference in the tensile strain sustained by MoS 2 flakes [37,39,40] rather than a difference in the doping levels caused by a dissimilarity in charge transfer for the two systems (if doping occurred, we would observe an up-shift of the A 1g mode while the E 1 2g mode remains unchanged [29,41] since graphene is p-doped, but this not the case here). The atomic displacements of these two modes are illustrated in Fig.…”

Section: Resultsmentioning

confidence: 98%

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: 98%

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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“…[12][13][14] Raman spectroscopy is often used to probe these two effects in the TMD films, because the two primary Raman modes, in-plane E2g mode and out-of-plane A1g mode, respond differently to the two effects: E2g is more sensitive to the strain than A1g, 15 while A1g is much more sensitive to the doping than E2g. 16 The deformation potentials under biaxial strain for the phonon modes and bandgap have been estimated to be −4.5 cm -1 /% for E2g, −1.0 cm -1 /% for A1g, 17 and −70 meV/% for bandgap, 18 respectively. Electron doping results in red-shifts of both Raman modes, but the E2g shift is about 1/9 of A1g.…”

Section: Introductionmentioning

confidence: 99%

In Situ Monitoring of the Thermal-Annealing Effect in a Monolayer of MoS2

Cao

et al. 2017

Phys. Rev. Applied

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We perform in-situ two-cycle thermal cycling and annealing studies for a transferred CVDgrown monolayer MoS2 on a SiO2/Si substrate, using spatially resolved micro-Raman and PL spectroscopy. After the thermal cycling and being annealed at 305 °C twice, the film morphology and film-substrate bonding are significantly modified, which together with the removal of polymer residues cause major changes in the strain and doping distribution over the film, and thus the optical properties. Before annealing, the strain associated with ripples in the transferred film dominates the spatial distributions of the PL peak position and intensity over the film; after annealing, the variation in film-substrate bonding, affecting both strain and doping, becomes the leading factor. This work reveals that the film-substrate bonding, and thus the strain and doping, is unstable under thermal stress, which is important for understanding the substrate effects on the optical and transport properties of the 2D material and their impact on device applications.

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“…In the lift‐off process, the devices were soaked in acetone and ethanol successively to remove the polymethylmethacrylate (PMMA). The evaporation of ethanol on the devices generates a capillary force that pulls down the SWNT to adhere on the silicon substrate partially 28. Figure 1b shows the typical AFM topographic image of a SWNT device with tapping mode.…”

Section: Resultsmentioning

confidence: 99%

Nanogap‐Engineerable Electromechanical System for Ultralow Power Memory

Zhang

Deng

et al. 2017

Advanced Science

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Nanogap engineering of low‐dimensional nanomaterials has received considerable interest in a variety of fields, ranging from molecular electronics to memories. Creating nanogaps at a certain position is of vital importance for the repeatable fabrication of the devices. Here, a rational design of nonvolatile memories based on sub‐5 nm nanogaped single‐walled carbon nanotubes (SWNTs) via the electromechanical motion is reported. The nanogaps are readily realized by electroburning in a partially suspended SWNT device with nanoscale region. The SWNT memory devices are applicable for both metallic and semiconducting SWNTs, resolving the challenge of separation of semiconducting SWNTs from metallic ones. Meanwhile, the memory devices exhibit excellent performance: ultralow writing energy (4.1 × 10−19 J bit−1), ON/OFF ratio of 105, stable switching ON operations, and over 30 h retention time in ambient conditions.

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Optoelectronic crystal of artificial atoms in strain-textured molybdenum disulphide

Cited by 382 publications

References 36 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

In Situ Monitoring of the Thermal-Annealing Effect in a Monolayer of MoS2

Nanogap‐Engineerable Electromechanical System for Ultralow Power Memory

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