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Jin Zhang, Yang Wei, Fengrui Yao, Dongqi Li, He Ma, Peng Lei, Hehai Fang, Xiaoyang Xiao, Zhixing Lu, Juehan Yang, Jingbo Li, Liying Jiao, Weida Hu, Kaihui Liu, Kai Liu, Peng Liu, Qunqing Li, Wei Lu, Shoushan Fan, Kaili Jiang
A vertical point heterostructure (VPH) is constructed by sandwiching a two-dimensional (2D) MoS2 flake with two cross-stacked metallic single-walled carbon nanotubes. It can be used as a field effect transistor with high on/off ratio and a light detector with high spatial resolution. Moreover, the hybrid 1D-2D-1D VPHs open up new possibilities for nanoelectronics and nanooptoelectronics.
December 6, 2016: Advanced Materials
Martin Ledinský, Bertrand Paviet-Salomon, Aliaksei Vetushka, Jonas Geissbühler, Andrea Tomasi, Matthieu Despeisse, Stefaan De Wolf, Christophe Ballif, Antonín Fejfar
Thin, light-absorbing films attenuate the Raman signal of underlying substrates. In this article, we exploit this phenomenon to develop a contactless thickness profiling method for thin films deposited on rough substrates. We demonstrate this technique by probing profiles of thin amorphous silicon stripes deposited on rough crystalline silicon surfaces, which is a structure exploited in high-efficiency silicon heterojunction solar cells. Our spatially-resolved Raman measurements enable the thickness mapping of amorphous silicon over the whole active area of test solar cells with very high precision; the thickness detection limit is well below 1 nm and the spatial resolution is down to 500 nm, limited only by the optical resolution...
December 6, 2016: Scientific Reports
Wei Wei, Ying Dai, Baibiao Huang
For in-plane heterostructures between 2D transition-metal dichalcogenides (TMDs), namely, MoSe2/MoS2, MoS2/MoSe2, WSe2/MoS2 and MoS2/WSe2, intrinsic strain can be introduced resulting from lattice mismatch between two constituents, which significantly influences electronic properties (straintronics). Intrinsic strain can reduce or decrease the coupling strength between nonmetal p and metal d orbitals, and therefore modifies the splitting between bonding and antibonding states at the high-symmetry k-points. In this case, relative upward or downward shift of band edge at specific k-points leads to band gap reduction or enhancement and the indirect-direct band gap transition...
December 5, 2016: Physical Chemistry Chemical Physics: PCCP
Qiyi Zhao, Yaohui Guo, Yixuan Zhou, Xianding Yan, Xinlong Xu
MoS2 based photoelectrodes with different thickness have been fabricated by liquid phase exfoliation and vacuum filtration method. Absorption spectra clearly demonstrated two splitting absorption peaks due to the spin-orbit coupling and first principle calculation also indicate the spin-orbit coupling effect. These results combined with the SEM and TEM measurement suggests that the randomly stacked MoS2 films can maintain the properties of few-layered materials with good quality. As a proof-of-principle applications, photoelectrochemical experiments of MoS2 based photoelectrodes manifests that these MoS2 films are one kind of reversible and stable optoelectronic materials with tunable microampere photocurrent as the change of film thickness...
November 16, 2016: Journal of Colloid and Interface Science
Junxi Duan, Xiaoming Wang, Xinyuan Lai, Guohong Li, Kenji Watanabe, Takashi Taniguchi, Mona Zebarjadi, Eva Y Andrei
Fast and controllable cooling at nanoscales requires a combination of highly efficient passive cooling and active cooling. Although passive cooling in graphene-based devices is quite effective due to graphene's extraordinary heat conduction, active cooling has not been considered feasible due to graphene's low thermoelectric power factor. Here, we show that the thermoelectric performance of graphene can be significantly improved by using hexagonal boron nitride (hBN) substrates instead of SiO2 We find the room temperature efficiency of active cooling in the device, as gauged by the power factor times temperature, reaches values as high as 10...
November 23, 2016: Proceedings of the National Academy of Sciences of the United States of America
Zhendong Wang, Qi Huang, Peng Chen, Shouhui Guo, Xiaoqing Liu, Xuelei Liang, Li Wang
Metal induced nucleation is adopted to achieve the growth of transition metal dichalcogenides at controlled locations. Ordered arrays of MoS2 and WS2 have successfully been fabricated on SiO2 substrates by using the patterned Pt/Ti dots as the nucleation sites. Uniform MoS2 monolayers with the adjustable size up to 50 μm are grown surrounding these metal patterns and the mobility of such layer is about 0.86 cm(2)/V·s. The crystalline flakes of WS2 are also fabricated extending from the metal patterns and the electron mobility of these flakes is up to 11...
December 2, 2016: Scientific Reports
Na Wu, Yadong Yu, Tao Li, Xiaojun Ji, Ling Jiang, Jiajun Zong, He Huang
Molybdenum disulfide, a type of two-dimensional layered material with unique properties, has been widely used in many fields. However, an exact understanding of its toxicity remains elusive, let alone its effects on the environmental microbial community. In this study, we utilized metabolomics technology to explore the effects of different concentrations of molybdenum disulfide nanosheets on Escherichia coli for the first time. The results showed that with increasing concentration of molybdenum disulfide nanosheets, the survival rate of Escherichia coli was decreased and the release of lactic dehydrogenase was increased...
2016: PloS One
Ruina Liu, Baoxin Liao, Xiangdong Guo, Debo Hu, Hai Hu, Luojun Du, Hua Yu, Guangyu Zhang, Xiaoxia Yang, Qing Dai
The performance of electronic circuits is becoming limited by on-chip digital information transmission. Graphene plasmons with ultra-high confinement and low damping rates offer an effective solution to this problem as they allow for the implementation of optical interconnects. However, direct contact with the semiconductor always deteriorates the plasmonic properties due to large damping of the plasmon in the semiconductor. Here, we studied graphene plasmons in heterostructures of graphene and monolayer MoS2 which represents a promising semiconductor for next-generation electronic devices...
December 1, 2016: Nanoscale
César J Lockhart de la Rosa, Amirhasan Nourbakhsh, Markus Heyne, Inge Asselberghs, Cedric Huyghebaert, Iuliana Radu, Marc Heyns, Stefan De Gendt
Despite rapid progress in 2D molybdenum disulfide (MoS2) research in recent years, MoS2 field-effect transistors (FETs) still suffer from a high metal-to-MoS2 contact resistance and low intrinsic mobility, which are major hindrances to their future application. We report an efficient technique to dope thin-film MoS2 FETs using a poly(vinyl-alcohol) (PVA) polymeric coating. This results in a reduction of the contact resistance by up to 30% as well as a reduction in the channel resistance to 20 kΩ sq(-1). Using a dehydration process, we were able to effectively control the surface interactions between MoS2 and the more electropositive hydroxyl groups (-OH) of PVA, which provided a controllable and yet reversible increase in the charge carrier density to a value of 8...
December 1, 2016: Nanoscale
G Deokar, N S Rajput, P Vancsó, F Ravaux, M Jouiad, D Vignaud, F Cecchet, J-F Colomer
Vertically aligned MoS2 nanosheets (NSs) with exposed edges were successfully synthesized over a large area (∼2 cm(2)). The NSs were grown using an ambient pressure chemical vapor deposition technique via rapid sulfurization of sputter deposited thick molybdenum films. Extensive characterization of the grown MoS2 NSs has been carried out using high resolution scanning and transmission electron microscopy (SEM & TEM). A special care was given to the TEM lamella preparation process by means of a focused ion beam to preserve the NS growth direction...
December 1, 2016: Nanoscale
Jiajia Lv, Sen Zhao, Shijia Wu, Zhouping Wang
Water safety is one of the most pervasive problems afflicting people throughout the world. Microcystin-LR (MC-LR), a representative toxin released by cyanobacteria, poses an increasing and serious threat to water safety. In order to develop facile, specific and sensitive detection methods for MC-LR, we fabricated an ultrasensitive fluorescence aptasensor using the enhanced fluorescence of UCNP and the effective quenching ability, high affinity toward single strand DNA (ssDNA) of MoS2 (termed as FAUM). This assay specifically determined MC-LR in the linear range of 0...
October 4, 2016: Biosensors & Bioelectronics
Bin Ouyang, Pengfei Ou, Yongjie Wang, Zetian Mi, Jun Song
The polymorphism of two dimensional MoS2 promises new possibilities for nanoelectronics. The realization of those possibilities necessitates techniques to enable flexible and controllable phase engineering of MoS2. In the present study, based on first-principles calculations, a new and flexible route to engineer the phase stability of MoS2 by interfacing it with a GaN or AlN substrate is reported. Depending on the surface termination of the underlying substrate, MoS2 may exhibit either the 2H or 1T' (1T'') phase...
November 29, 2016: Physical Chemistry Chemical Physics: PCCP
Arūnas Jagminas, Gediminas Niaura, Rokas Žalnėravičius, Romualdas Trusovas, Gediminas Račiukaitis, Vitalija Jasulaitiene
One-pot hydrothermal synthesis of MoS2 nanoplatelet arrays on various substrates is perhaps the most promising approach to fabricate efficient electrocatalysts for hydrogen evolution reaction. However, the main challenges in this synthesis remain the purity and crystallinity of MoS2. In this study, we show for the first time that irradiation of amorphous, defect-rich MoS2 nanoplatelets with a green nanosecond laser at a proper irradiation dose, ca ≤0.35 J cm(-2), can significantly improve the crystallinity and purity of MoS2 nanoplatelets...
November 28, 2016: Scientific Reports
Miaofei Meng, Xiying Ma
We investigated the surface morphologies, crystal structures, and optical characteristics of rare earth element erbium (Er)-doped MoS2 (Er: MoS2) thin films fabricated on Si substrates via chemical vapor deposition (CVD). The surface mopography, crystalline structure, light absorption property, and the photoelectronic characteristics of the Er: MoS2 films were studied. The results indicate that doping makes the crystallinity of MoS2 films better than that of the undoped film. Meanwhile, the electron mobility and conductivity of the Er-doped MoS2 films increase about one order of magnitude, and the current-voltage (I-V) and the photoelectric response characteristics of the Er:MoS2/Si heterojunction increase significantly...
December 2016: Nanoscale Research Letters
Meng Li, Jialin Shi, Lianqing Liu, Peng Yu, Ning Xi, Yuechao Wang
Physical properties of two-dimensional materials, such as graphene, black phosphorus, molybdenum disulfide (MoS2) and tungsten disulfide, exhibit significant dependence on their lattice orientations, especially for zigzag and armchair lattice orientations. Understanding of the atomic probe motion on surfaces with different orientations helps in the study of anisotropic materials. Unfortunately, there is no comprehensive model that can describe the probe motion mechanism. In this paper, we report a tribological study of MoS2 in zigzag and armchair orientations...
2016: Science and Technology of Advanced Materials
Muhammad Farooq Khan, Ghazanfar Nazir, Volodymyr M Lermolenko, Jonghwa Eom
The electrical and photo-electrical properties of exfoliated MoS2 were investigated in the dark and in the presence of deep ultraviolet (DUV) light under various environmental conditions (vacuum, N2 gas, air, and O2 gas). We examined the effects of environmental gases on MoS2 flakes in the dark and after DUV illumination through Raman spectroscopy and found that DUV light induced red and blue shifts of peaks (E(1)2 g and A1 g) position in the presence of N2 and O2 gases, respectively. In the dark, the threshold voltage in the transfer characteristics of few-layer (FL) MoS2 field-effect transistors (FETs) remained almost the same in vacuum and N2 gas but shifted toward positive gate voltages in air or O2 gas because of the adsorption of oxygen atoms/molecules on the MoS2 surface...
2016: Science and Technology of Advanced Materials
Chenghuan Jiang, Rongqing Zhou, Zhaohui Peng, Jinfu Zhu, Qian Chen
The fabrication of a transition metal (TM) atomically thin layer with robust ferromagnetic ordering (FM) for the continuous miniaturization of spintronic and quantum computing devices is desired. Through first-principles calculations, we establish that Ru atoms can be epitaxially aligned on MoS2 monolayers, thus forming an atomically thin layer of 2D Ru/MoS2 heterostructure with high structural stability. The Ru layer possesses a robust FM (more than 300 K) and an out-of-plane easy axis with the magnetic anisotropy energy (MAE) of ∼3...
November 30, 2016: Physical Chemistry Chemical Physics: PCCP
Yan Wang, Raymond Fullon, Muharrem Acerce, Christopher E Petoukhoff, Jieun Yang, Chenggan Chen, Songnan Du, Sin Ki Lai, Shu Ping Lau, Damien Voiry, Deirdre O'Carroll, Gautam Gupta, Aditya D Mohite, Shengdong Zhang, Hang Zhou, Manish Chhowalla
Integration of organic/inorganic hybrid perovskites with metallic or semiconducting phases of 2D MoS2 nanosheets via solution processing is demonstrated. The results show that the collection of charge carriers is strongly dependent on the electronic properties of the 2D MoS2 with metallic MoS2 showing high responsivity and the semiconducting phase exhibiting high on/off ratios.
November 21, 2016: Advanced Materials
Yun-Han Ma, Wei-Tao Dou, Yu-Fei Pan, Li-Wei Dong, Ye-Xiong Tan, Xiao-Peng He, He Tian, Hong-Yang Wang
A 2D peptidosheet unravels CD47 as a potential biomarker to image hepatocarcinoma and cholangiocarcinoma cells and tissues. Supramolecular assembly between water-soluble 2D MoS2 and a peptide probe produces the 2D peptidosheet suited for the profiling of hepatocarcinoma and cholangiocarcinoma tissues over healthy tissues on clinical specimens.
November 21, 2016: Advanced Materials
Ashmeet Singh, Nidhi Kapil, Mahesh Yenuganti, Dibyendu Das
We have developed a unique class of MoS2 entrapped aqueous gels where the exfoliated sheets trigger physical cross-linking of nanofibers of peptide amphiphiles. Strikingly, these aqueous gels show acute responsiveness towards near infra-red light (804 nm), an unprecedented observation for molecular hydrogels.
November 17, 2016: Chemical Communications: Chem Comm
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