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High-throughput bandstructure simulations of van der Waals hetero-bilayers formed by 1T and 2H monolayers npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-24 Rui Dong; Alain Jacob; Stéphane Bourdais; Stefano Sanvito
Vertically stacked van der Waals heterostructures made of two-dimensional compounds are almost an infinite playground for the fabrication of nano-engineered materials for the most diverse applications. Unfortunately, high-throughput electronic structure theory, which often serves as a guidance for material design, is not practical in this case. In fact, the compositional and structural complexity of
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Electron–phonon coupling in superconducting 1T-PdTe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-23 Gloria Anemone; Pablo Casado Aguilar; Manuela Garnica; Fabian Calleja; Amjad Al Taleb; Chia-Nung Kuo; Chin Shan Lue; Antonio Politano; Amadeo L. Vázquez de Parga; Giorgio Benedek; Daniel Farías; Rodolfo Miranda
We have determined the electron–phonon interaction in type II Dirac semimetallic 1T-PdTe2 by means of helium atom scattering. While 1T-PdTe2 is isostructural with 1T-PtTe2, only the former is superconductor. The difference can be traced to the substantially larger value of the electron–phonon coupling in 1T-PdTe2, λ = 0.58, obtained from the Debye-Waller attenuation of the He specular peak. With this
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Multiplexed neurochemical transmission emulated using a dual-excitatory synaptic transistor npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-22 Mingxue Ma; Yao Ni; Zirong Chi; Wanqing Meng; Haiyang Yu; Jiangdong Gong; Huanhuan Wei; Hong Han; Xinran Wang; Wentao Xu
The ability to emulate multiplexed neurochemical transmission is an important step toward mimicking complex brain activities. Glutamate and dopamine are neurotransmitters that regulate thinking and impulse signals independently or synergistically. However, emulation of such simultaneous neurotransmission is still challenging. Here we report design and fabrication of synaptic transistor that emulates
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In situ electron microscopy study of structural transformations in 2D CoSe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-22 Dnyaneshwar S. Gavhane; Heleen van Gog; Balu Thombare; Gaurav Lole; L. Christiaan Post; Mahendra A. More; Marijn A. van Huis
Thermally induced structural transformation of 2D materials opens unique avenues for generating other 2D materials by physical methods. Imaging these transitions in real time provides insight into synthesis routes and property tuning. We have used in situ transmission electron microscopy (TEM) to follow thermally induced structural transformations in layered CoSe2. Three transformation processes are
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Freestanding few-layer sheets of a dual topological insulator npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-18 Mai Lê Anh; Pavel Potapov; Axel Lubk; Thomas Doert; Michael Ruck
The emergence of topological insulators (TIs) raised high expectations for their application in quantum computers and spintronics. Being bulk semiconductors, their nontrivial topology at the electronic bandgap enables dissipation-free charge and spin transport in protected metallic surface states. For application, crystalline thin films are requested in sufficient quantity. A suitable approach is the
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2D graphene oxide–aptamer conjugate materials for cancer diagnosis npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-17 Simranjeet Singh Sekhon; Prabhsharan Kaur; Yang-Hoon Kim; Satpal Singh Sekhon
2D graphene oxide (GO) with large surface area, multivalent structure can easily bind single-stranded DNA/RNA (aptamers) through hydrophobic/π-stacking interactions, whereas aptamers having small size, excellent chemical stability and low immunogenicity bind to their targets with high affinity and specificity. GO–aptamer conjugate materials synthesized by integrating aptamers with GO can thus provide
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A mode-balanced reconfigurable logic gate built in a van der Waals strata npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-16 Wei Cao; Jae Hwan Chu; Kamyar Parto; Kaustav Banerjee
Two-dimensional (2D) semiconducting materials, in particular transition-metal dichalcogenides, have emerged as the preferred channel materials for sub-5 nm field-effect transistors (FETs). However, the lack of practical doping techniques for these materials poses a significant challenge to designing complementary logic gates containing both n- and p-type FETs. Although electrical tuning of the polarity
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Ultra-broad spectral photo-response in FePS 3 air-stable devices npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-15 Maria Ramos; Felix Carrascoso; Riccardo Frisenda; Patricia Gant; Samuel Mañas-Valero; Dorye L. Esteras; José J. Baldoví; Eugenio Coronado; Andres Castellanos-Gomez; M. Reyes Calvo
Van der Waals materials with narrow energy gaps and efficient response over a broadband optical spectral range are key to widen the energy window of nanoscale optoelectronic devices. Here, we characterize FePS3 as an appealing narrow-gap p-type semiconductor with an efficient broadband photo-response, a high refractive index, and a remarkable resilience against air and light exposure. To enable fast
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Two-dimensional iodine-monofluoride epitaxy on WSe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-02-10 Yung-Chang Lin; Sungwoo Lee; Yueh-Chiang Yang; Po-Wen Chiu; Gun-Do Lee; Kazu Suenaga
Interhalogen compounds (IHCs) are extremely reactive molecules used for halogenation, catalyst, selective etchant, and surface modification. Most of the IHCs are unstable at room temperature especially for the iodine-monofluoride (IF) whose structure is still unknown. Here we demonstrate an unambiguous observation of two-dimensional (2D) IF bilayer grown on the surface of WSe2 by using scanning transmission
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Reactive plasma cleaning and restoration of transition metal dichalcogenide monolayers npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-28 Daniil Marinov; Jean-François de Marneffe; Quentin Smets; Goutham Arutchelvan; Kristof M. Bal; Ekaterina Voronina; Tatyana Rakhimova; Yuri Mankelevich; Salim El Kazzi; Ankit Nalin Mehta; Pieter-Jan Wyndaele; Markus Hartmut Heyne; Jianran Zhang; Patrick C. With; Sreetama Banerjee; Erik C. Neyts; Inge Asselberghs; Dennis Lin; Stefan De Gendt
The cleaning of two-dimensional (2D) materials is an essential step in the fabrication of future devices, leveraging their unique physical, optical, and chemical properties. Part of these emerging 2D materials are transition metal dichalcogenides (TMDs). So far there is limited understanding of the cleaning of “monolayer” TMD materials. In this study, we report on the use of downstream H2 plasma to
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Terahertz optics-driven phase transition in two-dimensional multiferroics npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-22 Jian Zhou; Shunhong Zhang
Displacive martensitic phase transition is potentially promising in semiconductor-based data storage applications with fast switching speed. In addition to traditional phase transition materials, the recently discovered two-dimensional ferroic materials are receiving a lot of attention owing to their fast ferroic switching dynamics, which could tremendously boost data storage density and enhance read/write
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Giant persistent photoconductivity in monolayer MoS 2 field-effect transistors npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-11 A. George; M. V. Fistul; M. Gruenewald; D. Kaiser; T. Lehnert; R. Mupparapu; C. Neumann; U. Hübner; M. Schaal; N. Masurkar; L. M. R. Arava; I. Staude; U. Kaiser; T. Fritz; A. Turchanin
Monolayer transition metal dichalcogenides (TMD) have numerous potential applications in ultrathin electronics and photonics. The exposure of TMD-based devices to light generates photo-carriers resulting in an enhanced conductivity, which can be effectively used, e.g., in photodetectors. If the photo-enhanced conductivity persists after removal of the irradiation, the effect is known as persistent
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The role of device asymmetries and Schottky barriers on the helicity-dependent photoresponse of 2D phototransistors npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Jorge Quereda; Jan Hidding; Talieh S. Ghiasi; Bart J. van Wees; Caspar H. van der Wal; Marcos H. D. Guimarães
Circular photocurrents (CPC), namely circular photogalvanic (CPGE) and photon drag effects, have recently been reported both in monolayer and multilayer transition metal dichalcogenide (TMD) phototransistors. However, the underlying physics for the emergence of these effects are not yet fully understood. In particular, the emergence of CPGE is not compatible with the D3h crystal symmetry of two-dimensional
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Origins of genuine Ohmic van der Waals contact between indium and MoS 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Bum-Kyu Kim; Tae-Hyung Kim; Dong-Hwan Choi; Hanul Kim; Kenji Watanabe; Takashi Taniguchi; Heesuk Rho; Ju-Jin Kim; Yong-Hoon Kim; Myung-Ho Bae
The achievement of ultraclean Ohmic van der Waals (vdW) contacts at metal/transition-metal dichalcogenide (TMDC) interfaces would represent a critical step for the development of high-performance electronic and optoelectronic devices based on two-dimensional (2D) semiconductors. Herein, we report the fabrication of ultraclean vdW contacts between indium (In) and molybdenum disulfide (MoS2) and the
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Imaging and identification of point defects in PtTe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Kuanysh Zhussupbekov; Lida Ansari; John B. McManus; Ainur Zhussupbekova; Igor V. Shvets; Georg S. Duesberg; Paul K. Hurley; Farzan Gity; Cormac Ó Coileáin; Niall McEvoy
The properties and performance of two-dimensional (2D) materials can be greatly affected by point defects. PtTe2, a 2D material that belongs to the group 10 transition metal dichalcogenides, is a type-II Dirac semimetal, which has gained a lot of attention recently due to its potential for applications in catalysis, photonics, and spintronics. Here, we provide an experimental and theoretical investigation
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Passivation of InP solar cells using large area hexagonal-BN layers npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Vidur Raj; Dipankar Chugh; Lachlan E. Black; M. M. Shehata; Li Li; Felipe Kremer; Daniel H. Macdonald; Hark Hoe Tan; Chennupati Jagadish
Surface passivation is crucial for many high-performance solid-state devices, especially solar cells. It has been proposed that 2D hexagonal boron nitride (hBN) films can provide near-ideal passivation due to their wide bandgap, lack of dangling bonds, high dielectric constant, and easy transferability to a range of substrates without disturbing their bulk properties. However, so far, the passivation
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Electric field induced giant valley polarization in two dimensional ferromagnetic WSe 2 /CrSnSe 3 heterostructure npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Imran Khan; Brahim Marfoua; Jisang Hong
Valleytronics is receiving extensive research efforts. Thus, we investigated the electric field-induced valley polarization in the WSe2/CrSnSe3 heterostructures by varying the stacking order. The heterostructure shows indirect band gaps of 270 and 330 meV in the two most stable structures. The WSe2/CrSnSe3 heterostructure displays a ferromagnetic ground state with out-of-plane anisotropy (0.02 meV)
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Elastic flow instabilities and macroscopic textures in graphene oxide lyotropic liquid crystals npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-08 Jacek K. Wychowaniec; Maria Iliut; Bartłomiej Borek; Christopher Muryn; Oleksandr O. Mykhaylyk; Steve Edmondson; Aravind Vijayaraghavan
Graphene oxide (GO) forms a well-aligned lyotropic liquid crystal (LC) phase in aqueous dispersions at relatively low concentrations. Under a remarkably wide range of shear rates, we report hitherto unobserved shear-induced polarized light image patterns, a Maltese cross combined with shear banding, recorded in real time and in situ during rheological measurements. This is shown to be a result of elastic
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Indirect to direct band gap crossover in two-dimensional WS 2(1−x) Se 2x alloys npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-05 Cyrine Ernandes; Lama Khalil; Hela Almabrouk; Debora Pierucci; Biyuan Zheng; José Avila; Pavel Dudin; Julien Chaste; Fabrice Oehler; Marco Pala; Federico Bisti; Thibault Brulé; Emmanuel Lhuillier; Anlian Pan; Abdelkarim Ouerghi
In atomically thin transition metal dichalcogenide semiconductors, there is a crossover from indirect to direct band gap as the thickness drops to one monolayer, which comes with a fast increase of the photoluminescence signal. Here, we show that for different alloy compositions of WS2(1−x)Se2x this trend may be significantly affected by the alloy content and we demonstrate that the sample with the
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The band-edge excitons observed in few-layer NiPS 3 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-05 Ching-Hwa Ho; Tien-Yao Hsu; Luthviyah Choirotul Muhimmah
Band-edge excitons of few-layer nickel phosphorous trisulfide (NiPS3) are characterized via micro-thermal-modulated reflectance (μTR) measurements from 10 to 300 K. Prominent μTR features of the A exciton series and B are simultaneously detected near the band edge of NiPS3. The A exciton series contains two sharp A1 and A2 levels and one threshold-energy-related transition (direct gap, E∞), which are
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Facilely synthesized nitrogen-doped reduced graphene oxide functionalized with copper ions as electrocatalyst for oxygen reduction npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Nadia Garino; Juqin Zeng; Micaela Castellino; Adriano Sacco; Francesca Risplendi; Michele Re Fiorentin; Katarzyna Bejtka; Angelica Chiodoni; Damien Salomon; Jaime Segura-Ruiz; Candido F. Pirri; Giancarlo Cicero
Nitrogen-doped reduced graphene oxide is successfully synthesized and functionalized with hydroxylated copper ions via one-pot microwave-assisted route. The presence of cationic Cu coordinated to the graphene layer is fully elucidated through a set of experimental characterizations and theoretical calculations. Thanks to the presence of these hydroxyl-coordinated Cu2+ active sites, the proposed material
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Electron-beam-irradiated rhenium disulfide memristors with low variability for neuromorphic computing npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Sifan Li; Bochang Li; Xuewei Feng; Li Chen; Yesheng Li; Li Huang; Xuanyao Fong; Kah-Wee Ang
State-of-the-art memristors are mostly formed by vertical metal–insulator–metal (MIM) structure, which rely on the formation of conductive filaments for resistive switching (RS). However, owing to the stochastic formation of filament, the set/reset voltage of vertical MIM memristors is difficult to control, which results in poor temporal and spatial switching uniformity. Here, a two-terminal lateral
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Probing valley population imbalance in transition metal dichalcogenides via temperature-dependent second harmonic generation imaging npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Leonidas Mouchliadis; Sotiris Psilodimitrakopoulos; George Miltos Maragkakis; Ioanna Demeridou; George Kourmoulakis; Andreas Lemonis; George Kioseoglou; Emmanuel Stratakis
Degenerate minima in momentum space—valleys—provide an additional degree of freedom that can be used for information transport and storage. Notably, such minima naturally exist in the band structure of transition metal dichalcogenides (TMDs). When these atomically thin crystals interact with intense laser light, the second harmonic generated (SHG) field inherits special characteristics that reflect
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Ab initio perspective of ultra-scaled CMOS from 2D-material fundamentals to dynamically doped transistors npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Aryan Afzalian
Using accurate dissipative DFT-NEGF atomistic-simulation techniques within the Wannier-Function formalism, we give a fresh look at the possibility of sub-10-nm scaling for high-performance complementary metal oxide semiconductor (CMOS) applications. We show that a combination of good electrostatic control together with high mobility is paramount to meet the stringent roadmap targets. Such requirements
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Multiple machine learning approach to characterize two-dimensional nanoelectronic devices via featurization of charge fluctuation npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Kookjin Lee; Sangjin Nam; Hyunjin Ji; Junhee Choi; Jun-Eon Jin; Yeonsu Kim; Junhong Na; Min-Yeul Ryu; Young-Hoon Cho; Hyebin Lee; Jaewoo Lee; Min-Kyu Joo; Gyu-Tae Kim
Two-dimensional (2D) layered materials such as graphene, molybdenum disulfide (MoS2), tungsten disulfide (WSe2), and black phosphorus (BP) provide unique opportunities to identify the origin of current fluctuation, mainly arising from their large surface areas compared with those of their bulk counterparts. Among numerous material characterization techniques, nondestructive low-frequency (LF) noise
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Strong and tunable spin–orbit interaction in a single crystalline InSb nanosheet npj 2D Mater. Appl. (IF 9.324) Pub Date : 2021-01-04 Yuanjie Chen; Shaoyun Huang; Dong Pan; Jianhong Xue; Li Zhang; Jianhua Zhao; H. Q. Xu
A dual-gate InSb nanosheet field-effect device is realized and is used to investigate the physical origin and the controllability of the spin–orbit interaction in a narrow bandgap semiconductor InSb nanosheet. We demonstrate that by applying a voltage over the dual gate, efficiently tuning of the spin–orbit interaction in the InSb nanosheet can be achieved. We also find the presence of an intrinsic
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Self-driven WSe 2 photodetectors enabled with asymmetrical van der Waals contact interfaces npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-12-14 Changjian Zhou; Shouyong Zhang; Zhe Lv; Zichao Ma; Cui Yu; Zhihong Feng; Mansun Chan
Self-driven photodetectors that can detect light without any external voltage bias are important for low-power applications, including future internet of things, wearable electronics, and flexible electronics. While two-dimensional (2D) materials exhibit good optoelectronic properties, the extraordinary properties have not been fully exploited to realize high-performance self-driven photodetectors
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Unveiling giant hidden Rashba effects in two-dimensional Si 2 Bi 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-12-11 Seungjun Lee; Young-Kyun Kwon
Recently, it has been known that the hidden Rashba (R-2) effect in two-dimensional materials gives rise to a physical phenomenon called spin-layer locking (SLL). However, not only its underlying fundamental mechanism has been unclear, but also there are only a few materials exhibiting weak SLL. Here, through the first-principles density functional theory and model Hamiltonian calculation, we reveal
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Uncovering topographically hidden features in 2D MoSe 2 with correlated potential and optical nanoprobes npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-12-09 David Moore; Kiyoung Jo; Christine Nguyen; Jun Lou; Christopher Muratore; Deep Jariwala; Nicholas R. Glavin
Developing characterization strategies to better understand nanoscale features in two-dimensional nanomaterials is of crucial importance, as the properties of these materials are many times driven by nanoscale and microscale chemical and structural modifications within the material. For the case of large area monolayer MoSe2 flakes, kelvin probe force microscopy coupled with tip-enhanced photoluminescence
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Robust quantum point contact operation of narrow graphene constrictions patterned by AFM cleavage lithography npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-12-07 Péter Kun; Bálint Fülöp; Gergely Dobrik; Péter Nemes-Incze; István Endre Lukács; Szabolcs Csonka; Chanyong Hwang; Levente Tapasztó
Detecting conductance quantization in graphene nanostructures turned out more challenging than expected. The observation of well-defined conductance plateaus through graphene nanoconstrictions so far has only been accessible in the highest quality suspended or h-BN encapsulated devices. However, reaching low conductance quanta in zero magnetic field, is a delicate task even with such ultra-high mobility
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Selective nitrogen doping of graphene due to preferential healing of plasma-generated defects near grain boundaries npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-12-04 G. Robert Bigras; X. Glad; P. Vinchon; R. Martel; L. Stafford
Hyperspectral Raman IMAging (RIMA) is used to study spatially inhomogeneous polycrystalline monolayer graphene films grown by chemical vapor deposition. Based on principal component analysis clustering, distinct regions are differentiated and probed after subsequent exposures to the late afterglow of a microwave nitrogen plasma at a reduced pressure of 6 Torr (800 Pa). The 90 × 90 µm2 RIMA mapping
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Synthesis of epitaxial monolayer Janus SPtSe npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-11-20 Roberto Sant; Maxime Gay; Alain Marty; Simone Lisi; Rania Harrabi; Céline Vergnaud; Minh Tuan Dau; Xiaorong Weng; Johann Coraux; Nicolas Gauthier; Olivier Renault; Gilles Renaud; Matthieu Jamet
Janus single-layer transition metal dichalcogenides, in which the two chalcogen layers have a different chemical nature, push chemical composition control beyond what is usually achievable with van der Waals heterostructures. Here, we report such a Janus compound, SPtSe, which is predicted to exhibit strong Rashba spin–orbit coupling. We synthetized it by conversion of a single-layer of PtSe2 on Pt(111)
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Improving stability of organometallic-halide perovskite solar cells using exfoliation two-dimensional molybdenum chalcogenides npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-11-11 Meiying Liang; Adnan Ali; Abdelhak Belaidi; Mohammad Istiaque Hossain; Oskar Ronan; Clive Downing; Nouar Tabet; Stefano Sanvito; Fedwa EI-Mellouhi; Valeria Nicolosi
Organometallic-halide perovskite solar cells (PSCs) are emerging as the most promising next generation solar cell devices. However, the stability is still the main bottleneck of their further development. Here, we introduce two-dimensional (2D) molybdenum chalcogenides (MoS2 and MoSe2) (MCs) nanoflakes as a buffer layer between perovskite layer and hole transport layer (HTL) to improve the stability
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Ising ferromagnetism and robust half-metallicity in two-dimensional honeycomb-kagome Cr 2 O 3 layer npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-11-09 Arqum Hashmi; Kenta Nakanishi; Muhammad Umar Farooq; Tomoya Ono
In contrast to the current research on two-dimensional (2D) materials, which is mainly focused on graphene and transition metal dichalcogenide-like structures, studies on 2D transition metal oxides are rare. By using ab initio calculations along with Monte Carlo simulations and nonequilibrium Green’s function method, we demonstrate that the transition metal oxide monolayer (ML) of Cr2O3 is an ideal
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Naturally occurring van der Waals materials npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-29 Riccardo Frisenda; Yue Niu; Patricia Gant; Manuel Muñoz; Andres Castellanos-Gomez
The exfoliation of two naturally occurring van der Waals minerals, graphite and molybdenite, arouse an unprecedented level of interest by the scientific community and shaped a whole new field of research: 2D materials research. Several years later, the family of van der Waals materials that can be exfoliated to isolate 2D materials keeps growing, but most of them are synthetic. Interestingly, in nature
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Electrothermal transport induced material reconfiguration and performance degradation of CVD-grown monolayer MoS 2 transistors npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-28 Ansh; Jeevesh Kumar; Gaurav Sheoran; Mayank Shrivastava
Device and material reliability of 2-dimensional materials, especially CVD-grown MoS2, has remained un-addressed since 2011 when the first TMDC transistor was reported. For its potential application in next generation electronics, it is imperative to update our understanding of mechanisms through which MoS2 transistors’ performance degrades under long-term electrical stress. We report, for CVD-grown
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Specific stacking angles of bilayer graphene grown on atomic-flat and -stepped Cu surfaces npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-13 Hyeyeon Cho; Yohwan Park; Soyoung Kim; Taemin Ahn; Tae-Hwan Kim; Hee Cheul Choi
Bilayer graphene (BLG) exhibits unique properties depending on a stacking angle between the two layers of graphene. Although it has been known that BLGs having stacking angles of 0° and 30° can be obtained by chemical vapor deposition (CVD), not much is known yet about the effect of copper (Cu) surface on the decision of stacking angle, through which further fine control of the stacking angle could
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Synthesis of high-quality monolayer tungsten disulfide with chlorophylls and its application for enhancing bone regeneration npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-13 Yi-Wen Chen; Ming-You Shie; Chien-Hsuan Hsiao; Yu-Chun Liang; Ben Wang; I-Wen Peter Chen
Due to the population explosion of the 21st century, nearly one billion people are over 64 years of age and bone fracture is one of the most frequent problems facing both sexes because of osteoporosis. However, difficulty in enhancing bone regeneration to repair bone fracture poses challenges and thus, a two-dimensional monolayer material (i.e. tungsten disulfide (WS2)) could be one of the candidates
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Mechanochemical conversion kinetics of red to black phosphorus and scaling parameters for high volume synthesis npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-13 Samuel V. Pedersen; Florent Muramutsa; Joshua D. Wood; Chad Husko; David Estrada; Brian J. Jaques
Adopting black phosphorus (BP) as a material in electronic and optoelectronic device manufacturing requires the development and understanding of a large-scale synthesis technique. To that end, high-energy planetary ball milling is demonstrated as a scalable synthesis route, and the mechanisms and conversion kinetics of the BP phase transformation are investigated. During the milling process, media
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Robust ferromagnetism in wafer-scale monolayer and multilayer Fe 3 GeTe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-10-07 Ryan Roemer; Chong Liu; Ke Zou
Monolayer iron germanium telluride Fe3GeTe2, one of the typical two-dimensional ferromagnetic materials, hitherto, has only been studied by exfoliated micron-sized samples. We achieve high-quality wafer-scale growth of thin Fe3GeTe2 films by molecular beam epitaxy, greatly expanding the types of characterization tools employable and providing the possibility for its integration in devices like consumer
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Interaction dynamics and site-specific electronic recognition of DNA-nicks with 2D solid-state nanopores npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-09-08 Nagendra Athreya; Olgica Milenkovic; Jean-Pierre Leburton
Single-stranded breaks in the DNA backbone caused by many endogenous and exogenous agents often lead to double-stranded breaks that are known causes of chromosomal instabilities leading to copious diseases. We describe a label-free detection technique using two-dimensional (2D) solid-state nanopore field-effect transistors (FETs) to sense and map site-specific nicks in the DNA backbone. We use all-atom
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Elimination of the internal electrostatic field in two-dimensional GaN-based semiconductors npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-08-28 Yuping Jia; Zhiming Shi; Wantong Hou; Hang Zang; Ke Jiang; Yang Chen; Shanli Zhang; Zhanbin Qi; Tong Wu; Xiaojuan Sun; Dabing Li
GaN-based semiconductors are promising materials for solid-state optoelectronic applications. However, the strong internal electrostatic field (IEF) along the [0001] direction is a serious problem that harms the efficiency of lighting devices based on GaN-based semiconductors due to the quantum confined Stark effect. Here we theoretically predict a method, reducing the dimensions from bulk to two-dimensional
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Direct imaging, three-dimensional interaction spectroscopy, and friction anisotropy of atomic-scale ripples on MoS 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-08-26 Omur E. Dagdeviren; Ogulcan Acikgoz; Peter Grütter; Mehmet Z. Baykara
Theory predicts that two-dimensional (2D) materials may only exist in the presence of out-of-plane deformations on atomic length scales, frequently referred to as ripples. While such ripples can be detected via electron microscopy, their direct observation via surface-based techniques and characterization in terms of interaction forces and energies remain limited, preventing an unambiguous study of
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Bandgap engineering of two-dimensional semiconductor materials npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-08-24 A. Chaves; J. G. Azadani; Hussain Alsalman; D. R. da Costa; R. Frisenda; A. J. Chaves; Seung Hyun Song; Y. D. Kim; Daowei He; Jiadong Zhou; A. Castellanos-Gomez; F. M. Peeters; Zheng Liu; C. L. Hinkle; Sang-Hyun Oh; Peide D. Ye; Steven J. Koester; Young Hee Lee; Ph. Avouris; Xinran Wang; Tony Low
Semiconductors are the basis of many vital technologies such as electronics, computing, communications, optoelectronics, and sensing. Modern semiconductor technology can trace its origins to the invention of the point contact transistor in 1947. This demonstration paved the way for the development of discrete and integrated semiconductor devices and circuits that has helped to build a modern society
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Author Correction: Dielectric properties of hexagonal boron nitride and transition metal dichalcogenides: from monolayer to bulk npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-08-18 Akash Laturia; Maarten L. Van de Put; William G. Vandenberghe
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Titanium disulfide as Schottky/ohmic contact for monolayer molybdenum disulfide npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-31 Junsen Gao; Manisha Gupta
2D semiconductors like Molybdenum disulfide (MoS2) still have issues in forming good metal electrode (Schottky and Ohmic) especially for mono layer (ML) to few layers thick due to strain and metallization issues. Here, we explore a 2D semi-metal, titanium disulfide (TiS2), for making different types of contacts with ML MoS2 using density functional theory (DFT). It is observed that ML TiS2 induces
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Photon-generated carrier transfer process from graphene to quantum dots: optical evidences and ultrafast photonics applications npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-31 X. Wang; X. H. Li; C. Jiang; C. T. A. Brown; J. Q. Ning; K. Zhang; Q. Yu; X. T. Ge; Q. J. Wang; Z. Y. Zhang
Graphene/III–V semiconductor van der Waals (vdW) heterostructures offer potential access to physics, functionalities, and superior performance of optoelectronic devices. Nevertheless, the lack of a bandgap in graphene severely restricts the controllability of carrier properties and therefore impedes its applications. Here, we demonstrate the engineering of graphene bandgap in the graphene/GaAs heterostructure
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Confined transverse-electric graphene plasmons in negative refractive-index systems npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-29 Xinyan Zhang; Hao Hu; Xiao Lin; Lian Shen; Baile Zhang; Hongsheng Chen
Transverse electric graphene plasmons are generally weakly confined in the direction perpendicular to the graphene plane. They are featured by a skin depth δ, namely the penetration depth of their evanescent fields into the surrounding environment, much larger than the wavelength λ in free space (e.g., δ > 10λ). The weak spatial confinement of transverse electric graphene plasmons is now the key drawback
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Two-dimensional forms of robust CO 2 reduction photocatalysts npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-16 Steven B. Torrisi; Arunima K. Singh; Joseph H. Montoya; Tathagata Biswas; Kristin A. Persson
Photoelectrocatalysts that use sunlight to power the CO2 reduction reaction will be crucial for carbon-neutral power and energy-efficient industrial processes. Scalable photoelectrocatalysts must satisfy a stringent set of criteria, such as stability under operating conditions, product selectivity, and efficient light absorption. Two-dimensional materials can offer high specific surface area, tunability
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Superposition of semiconductor and semi-metal properties of self-assembled 2D SnTiS 3 heterostructures npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-15 Srinivasa Reddy Tamalampudi; Jin-You Lu; Nitul Rajput; Chia-Yun Lai; Boulos Alfakes; Raman Sankar; Harry Apostoleris; Shashikant P. Patole; Ibraheem Almansouri; Matteo Chiesa
Two-dimensional metal dichalcogenide/monochalcogenide thin flakes have attracted much attention owing to their remarkable electronic and electrochemical properties; however, chemical instability limits their applications. Chemical vapor transport (CVT)-synthesized SnTiS3 thin flakes exhibit misfit heterojunction structure and are highly stable in ambient conditions, offering a great opportunity to
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Exciton–phonon interactions in nanocavity-integrated monolayer transition metal dichalcogenides npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-10 David Rosser; Taylor Fryett; Albert Ryou; Abhi Saxena; Arka Majumdar
Cavity-integrated transition metal dichalcogenide (TMDCs) excitons have recently emerged as a promising platform to study strong light–matter interactions and related cavity quantum electrodynamics phenomena. Although this exciton-cavity system is typically modeled as coupled harmonic oscillators, to account for the rich solid-state environment, the effect of exciton–phonon interaction needs to be
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Broadband optical properties of monolayer and bulk MoS 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-10 Georgy A. Ermolaev; Yury V. Stebunov; Andrey A. Vyshnevyy; Dmitry E. Tatarkin; Dmitry I. Yakubovsky; Sergey M. Novikov; Denis G. Baranov; Timur Shegai; Alexey Y. Nikitin; Aleksey V. Arsenin; Valentyn S. Volkov
Layered semiconductors such as transition metal dichalcogenides (TMDs) offer endless possibilities for designing modern photonic and optoelectronic components. However, their optical engineering is still a challenging task owing to multiple obstacles, including the absence of a rapid, contactless, and the reliable method to obtain their dielectric function as well as to evaluate in situ the changes
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Topologically protected spin diffusion and spin generator using chalcogenide superlattices npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-10 Junji Tominaga; Noriyuki Miyata; Satoshi Sumi; Hiroyuki Awano; Shuichi Murakami
Spintronics is expected to be the basis for future ultra-low-energy nanoelectronic devices. To operate such devices at room temperature, amplifiers, batteries, capacitors, as well as spin current sources are required. Here we report a chalcogenide superlattice composed of GeTe and Sb2Te3 layers that have a topologically protected spin diffusion length exceeding 100 μm at room temperature. A spin generator
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Bias-controlled plasmon switching in lithium-doped graphene on dielectric model Al 2 O 3 substrate npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-07-06 Vito Despoja; Josip Jakovac; Neven Golenić; Leonardo Marušić
Graphene doped by lithium atoms supports a strong Dirac plasmon, a weak acoustic plasmon and a strong interband plasmon Li(π + σ). Here we demonstrate that applying a positive or negative bias on the lithium-doped graphene causes the appearance (‘switching ON’) or disappearance (‘switching OFF’) of the Li(π + σ) plasmon and the ‘conversion’ of the Dirac plasmon into a strong acoustic plasmon. This
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Monolayer WSe2 induced giant enhancement in the spin Hall efficiency of Tantalum npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-06-23 Punyashloka Debashis; Terry Y. T. Hung; Zhihong Chen
Spin Orbit Torque Magnetic RAM (SOT-MRAM) is emerging as a promising memory technology owing to its high endurance, reliability and speed. A critical factor for its success is the development of materials that exhibit efficient conversion of charge current to spin current, characterized by their spin Hall efficiency. In this work, it is experimentally demonstrated that the spin Hall efficiency of the
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2D materials for spintronic devices npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-06-18 Ethan C. Ahn
2D materials are attractive for nanoelectronics due to their ultimate thickness dimension and unique physical properties. A wide variety of emerging spintronic device concepts will greatly benefit from the use of 2D materials, leading a better way to manipulating spin. In this review, we discuss various 2D materials, including graphene and other inorganic 2D semiconductors, in the context of scientific
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Sub-picosecond photo-induced displacive phase transition in two-dimensional MoTe 2 npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-06-12 Bo Peng; Hao Zhang; Weiwen Chen; Bowen Hou; Zhi-Jun Qiu; Hezhu Shao; Heyuan Zhu; Bartomeu Monserrat; Desheng Fu; Hongming Weng; Costas M. Soukoulis
Photo-induced phase transitions (PIPTs) provide an ultrafast, energy-efficient way for precisely manipulating the topological properties of transition-metal ditellurides and can be used to stabilize a topological phase in an otherwise semiconducting material. Using first-principles calculations, we demonstrate that the PIPT in monolayer MoTe2 from the semiconducting 2H phase to the topological 1T′
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Gate-switchable rectification in isotype van der Waals heterostructure of multilayer MoTe 2 /SnS 2 with large band offsets npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-06-12 Seonyeong Kim; Hyewon Du; Taekwang Kim; Somyeong Shin; Hyeon-kyo Song; Hansung Kim; Dain Kang; Chang-Won Lee; Sunae Seo
Despite intensive studies on van der Waals heterostructures based on two-dimensional layered materials, isotype vdW heterojunctions, which consist of two different semiconductors with the same majority carrier, have received little attention. We demonstrate an n–n isotype field-effect heterojunction device composed of multilayer moly ditelluride (MoTe2) and tin disulfide (SnS2). The carrier transport
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Direct visualization of out-of-equilibrium structural transformations in atomically thin chalcogenides npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-06-12 Pawan Kumar; James P. Horwath; Alexandre C. Foucher; Christopher C. Price; Natalia Acero; Vivek B. Shenoy; Eric A. Stach; Deep Jariwala
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) have been the subject of sustained research interest due to their extraordinary electronic and optical properties. They also exhibit a wide range of structural phases because of the different orientations that the atoms can have within a single layer, or due to the ways that different layers can stack. Here we report a unique study involving
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Application of Raman spectroscopy to probe fundamental properties of two-dimensional materials npj 2D Mater. Appl. (IF 9.324) Pub Date : 2020-05-26 Xin Cong; Xue-Lu Liu; Miao-Ling Lin; Ping-Heng Tan
Two-dimensional materials (2DMs), with remarkably electronic, optical, and mechanical properties, exhibit both high scientific interest and huge application potential. Raman spectroscopy has been proven to be a fast, convenient, and nondestructive technique to characterize the fundamental properties of 2DMs at both laboratory and mass-production scales. In this review, we discuss recent advances in
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