Search query: One-Step Synthesis of Metal/Semiconductor Heterostructure NbS2/MoS2

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abstract: Chemical vapor deposition (CVD) has proven its surpassing advantages, such as larger scale, interlayer orientation control, and clean interface, in the synthesis of transitional metal dichalcogenide (TMDC) semiconductor/semiconductor van der Waals (vdW) heterostructures. However, it is suffering problems of high melting points and low chemical reactivity of metal oxide feedstocks in the preparation of high quality metal/semiconductor (M/S) TMDC vdW heterostructures. Here, for the first time, we report the synthesis of the M/S TMDC vdW heterostructure NbS2/MoS2 via a one step halide assisted CVD method, which effectively overcomes the drawbacks of metal oxide precursors. This one step method provides the high quality and clean interface of the NbS2/MoS2 heterostructure, which has been proved by the transmission electron microscopy characterization. A mechanism that MoS2 finishes the growth first and subsequently serves as a superior substrate for the growth of NbS2 is proposed. This novel method will open
author_names: Qundong Fu

Xiaowei Wang

Jiadong Zhou

Juan Juan Xia

Qingsheng Zeng

Danhui Lv

Chao Zhu

Xiaolei Wang

Yue Shen

Xiaomin Li

Younan Hua

Fucai Liu

Zexiang Shen

Chuanhong Jin

Zheng Liu
title: One Step Synthesis of Metal/Semiconductor Heterostructure NbS2/MoS2
year: 2018

abstract: Two dimensional materials are an emerging class of new materials with a wide range of electrical properties and potential practical applications. Although graphene is the most well studied two dimensional material, single layers of other materials, such as insulating BN (ref. 2) and semiconducting MoS2 (refs 3, 4) or WSe2 (refs 5, 6) are gaining increasing attention as promising gate insulators and channel materials for field effect transistors. Because monolayer MoS2 is a direct bandgap semiconductor due to quantum mechanical confinement, it could be suitable for applications in optoelectronic devices where the direct bandgap would allow a high absorption coefficient and efficient electron hole pair generation under photoexcitation. Here, we demonstrate ultrasensitive monolayer MoS2 phototransistors with improved device mobility and ON current. Our devices show a maximum external photoresponsivity of 880 A W( 1) at a wavelength of 561 nm and a photoresponse in the 400 680 nm range. With recent developments in large scale production techniques such as liquid scale exfoliation and chemical vapour deposition like growth, MoS2 shows important potential for applications in MoS2 based integrated optoelectronic circuits, light sensing, biomedical imaging, video recording and spectroscopy.
author_names: Oriol Lopez-Sanchez

Dominik S Lembke

M Kayci

Aleksandra Radenovic

Andras Kis
title: Ultrasensitive photodetectors based on monolayer MoS2.
venue: Nature nanotechnology
year: 2013

abstract: Two dimensional materials are attractive for use in next generation nanoelectronic devices because, compared to one dimensional materials, it is relatively easy to fabricate complex structures from them. The most widely studied two dimensional material is graphene, both because of its rich physics and its high mobility. However, pristine graphene does not have a bandgap, a property that is essential for many applications, including transistors. Engineering a graphene bandgap increases fabrication complexity and either reduces mobilities to the level of strained silicon films or requires high voltages. Although single layers of MoS(2) have a large intrinsic bandgap of 1.8 eV (ref. 16) previously reported mobilities in the 0.5 3 cm(2) V( 1) s( 1) range are too low for practical devices. Here, we use a halfnium oxide gate dielectric to demonstrate a room temperature single layer MoS(2) mobility of at least 200 cm(2) V( 1) s( 1) similar to that of graphene nanoribbons, and demonstrate transistors with room temperature current on/off ratios of 1 x 10(8) and ultralow standby power dissipation. Because monolayer MoS(2) has a direct bandgap, it can be used to construct interband tunnel FETs, which offer lower power consumption than classical transistors. Monolayer MoS(2) could also complement graphene in applications that require thin transparent semiconductors, such as optoelectronics and energy harvesting.
author_names: Branimir Radisavljevic

Aleksandra Radenovic

Jacopo Brivio

Valentina Giacometti

Andras Kis
title: Single layer MoS2 transistors.
venue: Nature nanotechnology
year: 2011

abstract: Large area MoS(2) atomic layers are synthesized on SiO(2) substrates by chemical vapor deposition using MoO(3) and S powders as the reactants. Optical, microscopic and electrical measurements suggest that the synthetic process leads to the growth of MoS(2) monolayer. The TEM images verify that the synthesized MoS(2) sheets are highly crystalline.
author_names: Yi-Hsien Lee

Xin-Quan Zhang

Wenjing Zhang

M T Chang

Cheng-Te Lin

Kai Chang

Ya-Chu Yu

Jacob Tse-Wei Wang

Chia-Seng Chang

Lain-Jong Li

Tsung-Wu Lin
title: Synthesis of large area MoS2 atomic layers with chemical vapor deposition.
venue: Advanced materials
year: 2012

abstract: A new phototransistor based on the mechanically exfoliated single layer MoS(2) nanosheet is fabricated, and its light induced electric properties are investigated in detail. Photocurrent generated from the phototransistor is solely determined by the illuminated optical power at a constant drain or gate voltage. The switching behavior of photocurrent generation and annihilation can be completely finished within ca. 50 ms, and it shows good stability. Especially, the single layer MoS(2) phototransistor exhibits a better photoresponsivity as compared with the graphene based device. The unique characteristics of incident light control, prompt photoswitching, and good photoresponsivity from the MoS(2) phototransistor pave an avenue to develop the single layer semiconducting materials for multifunctional optoelectronic device applications in the future.
author_names: Zongyou Yin

Hai Li

Hong Li

Lin Jiang

Yumeng Shi

Yinghui Sun

Gang Lu

Qing Yu Zhang

Xiaodong Chen

Hua Zhang
title: Single layer MoS2 phototransistors.
venue: ACS nano
year: 2012

abstract: 2D metal semiconductor heterostructures based on transition metal dichalcogenides (TMDs) are considered as intriguing building blocks for various fields, such as contact engineering and high frequency devices. Although, a series of p n junctions utilizing semiconducting TMDs have been constructed hitherto, the realization of such a scheme using 2D metallic analogs has not been reported. Here, the synthesis of uniform monolayer metallic NbS2 on sapphire substrate with domain size reaching to a millimeter scale via a facile chemical vapor deposition (CVD) route is demonstrated. More importantly, the epitaxial growth of NbS2 WS2 lateral metal semiconductor heterostructures via a "two step" CVD method is realized. Both the lateral and vertical NbS2 WS2 heterostructures are achieved here. Transmission electron microscopy studies reveal a clear chemical modulation with distinct interfaces. Raman and photoluminescence maps confirm the precisely controlled spatial modulation of the as grown NbS2 WS2 heterostructures. The existence of the NbS2 WS2 heterostructures is further manifested by electrical transport measurements. This work broadens the horizon of the in situ synthesis of TMD based heterostructures and enlightens the possibility of applications based on 2D metal semiconductor heterostructures.
author_names: Yu Zhang

Lei Yin

Junwei Chu

Tofik Ahmed Shifa

Jing Xia

Feng Wang

Yao Wen

Xueying Zhan

Zhenxing Wang

Jun He
title: Edge Epitaxial Growth of 2D NbS2 WS2 Lateral Metal Semiconductor Heterostructures.
venue: Advanced materials
year: 2018

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.
author_names: Yongji Gong

Junhao Lin

Xingli Wang

Gang Shi

Sidong Lei

Zhong Lin

Xiaolong Zou

Gonglan Ye

Robert Vajtai

Boris I Yakobson

Humberto Terrones

Mauricio Terrones

Bengkang Tay

Jun Lou

Sokrates T Pantelides

Zheng Liu

Wu Zhou

Pulickel M Ajayan
title: Vertical and in plane heterostructures from WS2/MoS2 monolayers.
venue: Nature materials
year: 2014

abstract: Electronic and spintronic devices rely on the fact that free charge carriers in solids carry electric charge and spin. There are, however, other properties of charge carriers that might be exploited in new families of devices. In particular, if there are two or more minima in the conduction band (or maxima in the valence band) in momentum space, and if it is possible to confine charge carriers in one of these valleys, then it should be possible to make a valleytronic device. Valley polarization, as the selective population of one valley is designated, has been demonstrated using strain and magnetic fields, but neither of these approaches allows dynamic control. Here, we demonstrate that optical pumping with circularly polarized light can achieve complete dynamic valley polarization in monolayer MoS(2) (refs 11, 12) a two dimensional non centrosymmetric crystal with direct energy gaps at two valleys. Moreover, this polarization is retained for longer than 1 ns. Our results, and similar results by Zeng et al. demonstrate the viability of optical valley control and suggest the possibility of valley based electronic and optoelectronic applications in MoS(2) monolayers.
author_names: Kin Fai Mak

Keliang He

Jie Shan

Tony F Heinz
title: Control of valley polarization in monolayer MoS2 by optical helicity.
venue: Nature nanotechnology
year: 2012

abstract: Transition metal dichalcogenides (TMDs) have attracted considerable interest for exploration of next generation electronics and optoelectronics in recent years. Fabrication of in plane lateral heterostructures between TMDs has opened up excellent opportunities for engineering two dimensional materials. The creation of high quality heterostructures with a facile method is highly desirable but it still remains challenging. In this work, we demonstrate a one step growth method for the construction of high quality MoS2 WS2 in plane heterostructures. The synthesis was carried out using ambient pressure chemical vapor deposition (APCVD) with the assistance of sodium chloride (NaCl) It was found that the addition of NaCl played a key role in lowering the growth temperatures, in which the Na containing precursors could be formed and condensed on the substrates to reduce the energy of the reaction. As a result, the growth regimes of MoS2 and WS2 are better matched, leading to the formation of in plane heterostructures in a single step. The heterostructures were proved to be of high quality with a sharp and clear interface. This newly developed strategy with the assistance of NaCl is promising for synthesizing other TMDs and their heterostructures.
author_names: Zhan Wang

Yong Xie

Haolin Wang

Ruixue Wu

Tang Nan

Yongjie Zhan

Jing Sun

Teng Jiang

Ying Zhao

Yimin Lei

Mei Yang

Weidong Wang

Qing Zhu

Xiao-hua Ma

Yue Hao
title: NaCl assisted one step growth of MoS2 WS2 in plane heterostructures.
venue: Nanotechnology
year: 2017

abstract: Research on graphene and other two dimensional atomic crystals is intense and is likely to remain one of the leading topics in condensed matter physics and materials science for many years. Looking beyond this field, isolated atomic planes can also be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. The first, already remarkably complex, such heterostructures (often referred to as 'van der Waals' have recently been fabricated and investigated, revealing unusual properties and new phenomena. Here we review this emerging research area and identify possible future directions. With steady improvement in fabrication techniques and using graphene's springboard, van der Waals heterostructures should develop into a large field of their own.
author_names: Andre K Geim

Irina Vladimirovna Grigorieva
title: Van der Waals heterostructures
venue: Nature
year: 2013