One-Step CVD Synthesis of Few-Layer SnS2/MoS2 Vertical Heterostructures
TL;DR: For controllable fabrication of van der Waals (vdW) heterostructures with various-layered two-dimensional (2D) materials is attractive to design various materials and devices.
Abstract: Constructing van der Waals (vdW) heterostructures with various-layered two-dimensional (2D) materials is attractive to design various materials and devices. For controllable fabrication of vdW hete...
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TL;DR: The tin sulfide (SnxSy) class of materials has attracted tremendous research interest in recent years owing to their intriguing physicochemical properties as mentioned in this paper, and the recent progress in their synthesis, properties, and applications.
Abstract: The tin sulfide (SnxSy) class of materials has attracted tremendous research interest in recent years owing to their intriguing physicochemical properties. Their inimitable optical, electronic, and mechanical properties open up windows for a broad range of promising applications. The precise design and tuning of the crystal phase, size, thickness, and composition holds excellent potential for utilizing them as crucial components of advanced devices. In this review, we explore the recent progress in their synthesis, properties, and applications. Initially, we outline the SnxSy class of materials briefly and discuss the recent developments in their phase and crystal dependent physicochemical properties. Numerous strategies have been portrayed for the preparation of single- to multi-layer, zero dimension to three dimension, and nano-sized to micro-sized materials. In-depth information on synthesis methods has been explored under the top-down and bottom-up approaches. The review includes the properties and synthesis of tin sulfides and also delivers exciting progress in various fields of applications. Finally, the prospects and opportunities in these exciting fields are discussed, based on their current progress.
25 citations
TL;DR: In this article , a state-of-the-art review regarding the current research progress of performance modulation of 2D van der Waals (vdW) heterostructures by different techniques is presented.
Abstract: 2D van der Waals (vdW) heterostructures are receiving increasing research attention due to the theoretically amazing properties and unprecedented application potential. However, the as-synthesized heterostructures are generally underperforming due to the weak interlayer coupling, which inspires the researchers to find ways to modulate the interlayer coupling and properties, realizing the tailored performance for actual applications. There have been a lot of publications regarding the controllable regulation of the structures and properties of 2D vdW heterostructures in the past few years, while a review work summarizing the current advances is not yet available, though it is significant. This paper conducts a state-of-the-art review regarding the current research progress of performance modulation of vdW heterostructures by different techniques. First, the general synthesis methods of vdW heterostructures are summarized. Then, different performance modulation techniques, that is, mechanical-based, external fields-assisted, and particle beam irradiation-based methods, are discussed and compared in detail. Some of the newly proposed concepts are described. Thereafter, applications of vdW heterostructures with tailored properties are reviewed for the application prospects of the topic around this area. Moreover, the future research challenges and prospects are discussed, aiming at triggering more research interest and device applications around this topic.
13 citations
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TL;DR: This work exemplifies the evolution of structural parameters in layered materials in changing from the three-dimensional to the two-dimensional regime by characterized by Raman spectroscopy.
Abstract: Molybdenum disulfide (MoS2) of single- and few-layer thickness was exfoliated on SiO2/Si substrate and characterized by Raman spectroscopy. The number of S−Mo−S layers of the samples was independently determined by contact-mode atomic force microscopy. Two Raman modes, E12g and A1g, exhibited sensitive thickness dependence, with the frequency of the former decreasing and that of the latter increasing with thickness. The results provide a convenient and reliable means for determining layer thickness with atomic-level precision. The opposite direction of the frequency shifts, which cannot be explained solely by van der Waals interlayer coupling, is attributed to Coulombic interactions and possible stacking-induced changes of the intralayer bonding. This work exemplifies the evolution of structural parameters in layered materials in changing from the three-dimensional to the two-dimensional regime.
3,969 citations
TL;DR: A one-step growth strategy for the creation of high-quality vertically stacked as well as in-plane interconnected heterostructures of WS2/MoS2 via control of the growth temperature is reported.
Abstract: Layer-by-layer stacking or lateral interfacing of atomic monolayers has opened up unprecedented opportunities to engineer two-dimensional heteromaterials. Fabrication of such artificial heterostructures with atomically clean and sharp interfaces, however, is challenging. Here, we report a one-step growth strategy for the creation of high-quality vertically stacked as well as in-plane interconnected heterostructures of WS2/MoS2 via control of the growth temperature. Vertically stacked bilayers with WS2 epitaxially grown on top of the MoS2 monolayer are formed with preferred stacking order at high temperature. A strong interlayer excitonic transition is observed due to the type II band alignment and to the clean interface of these bilayers. Vapour growth at low temperature, on the other hand, leads to lateral epitaxy of WS2 on MoS2 edges, creating seamless and atomically sharp in-plane heterostructures that generate strong localized photoluminescence enhancement and intrinsic p-n junctions. The fabrication of heterostructures from monolayers, using simple and scalable growth, paves the way for the creation of unprecedented two-dimensional materials with exciting properties.
1,919 citations
TL;DR: A reverse flow during the temperature-swing stage in the sequential vapor deposition growth process allowed us to cool the existing 2D crystals to prevent undesired thermal degradation and uncontrolled homogeneous nucleation, thus enabling highly robust block-by-block epitaxial growth.
Abstract: We report a general synthetic strategy for highly robust growth of diverse lateral heterostructures, multiheterostructures, and superlattices from two-dimensional (2D) atomic crystals. A reverse flow during the temperature-swing stage in the sequential vapor deposition growth process allowed us to cool the existing 2D crystals to prevent undesired thermal degradation and uncontrolled homogeneous nucleation, thus enabling highly robust block-by-block epitaxial growth. Raman and photoluminescence mapping studies showed that a wide range of 2D heterostructures (such as WS2-WSe2 and WS2-MoSe2), multiheterostructures (such as WS2-WSe2-MoS2 and WS2-MoSe2-WSe2), and superlattices (such as WS2-WSe2-WS2-WSe2-WS2) were readily prepared with precisely controlled spatial modulation. Transmission electron microscope studies showed clear chemical modulation with atomically sharp interfaces. Electrical transport studies of WSe2-WS2 lateral junctions showed well-defined diode characteristics with a rectification ratio up to 105.
486 citations
TL;DR: This work demonstrates for the first time a two-step chemical vapor deposition (CVD) method for growing transition-metal dichalcogenide (TMD) heterostructures, where MoSe 2 was synthesized first and followed by an epitaxial growth of WSe2 on the edge and on the top surface of MoSe2.
Abstract: Two dimensional (2D) materials have attracted great attention due to their unique properties and atomic thickness. Although various 2D materials have been successfully synthesized with different optical and electrical properties, a strategy for fabricating 2D heterostructures must be developed in order to construct more complicated devices for practical applications. Here we demonstrate for the first time a two-step chemical vapor deposition (CVD) method for growing transition-metal dichalcogenide (TMD) heterostructures, where MoSe2 was synthesized first and followed by an epitaxial growth of WSe2 on the edge and on the top surface of MoSe2. Compared to previously reported one-step growth methods, this two-step growth has the capability of spatial and size control of each 2D component, leading to much larger (up to 169 μm) heterostructure size, and cross-contamination can be effectively minimized. Furthermore, this two-step growth produces well-defined 2H and 3R stacking in the WSe2/MoSe2 bilayer regions ...
464 citations
TL;DR: A novel approach to the controlled synthesis of thin crystal arrays of SnS(2) at predefined locations on chip by chemical vapor deposition with seed engineering is reported, which opens a pathway for the large-scale production of layered 2D semiconductor devices, important for applications in integrated nanoelectronic/photonic systems.
Abstract: Layered two-dimensional (2D) semiconductors, such as MoS2 and SnS2, have been receiving intensive attention due to their technological importance for the next-generation electronic/photonic applications. We report a novel approach to the controlled synthesis of thin crystal arrays of SnS2 at predefined locations on chip by chemical vapor deposition with seed engineering and have demonstrated their application as fast photodetectors with photocurrent response time ∼5 μs. This opens a pathway for the large-scale production of layered 2D semiconductor devices, important for applications in integrated nanoelectronic/photonic systems.
415 citations