Deep Learning Enabled Strain Mapping of Single-Atom Defects in 2D Transition Metal Dichalcogenides with Sub-picometer Precision
Chia-Hao Lee, Abid Khan, Di Luo, Tatiane P. Santos, Chuqiao Shi, Blanka E. Janicek, Sangmin Kang, Wenjuan Zhu, Nahil A. Sobh, André Schleife, Bryan K. Clark, Pinshane Y. Huang
备注：
All authors are from University of Illinois at Urbana-Champaign. 41 pages, 5 figures, 6 supplementary figures, and supplementary information
2D materials offer an ideal platform to study the strain fields induced by individual atomic defects, yet challenges associated with radiation damage have so-far limited electron microscopy methods to probe these atomic-scale strain fields. Here, we demonstrate an approach to probe single-atom defects with sub-picometer precision in a monolayer 2D transition metal dichalcogenide, WSe$_{2-2x}$Te$_{2x}$. We utilize deep learning to mine large datasets of aberration-corrected scanning transmission electron microscopy images to locate and classify point defects. By combining hundreds of images of nominally identical defects, we generate high signal-to-noise class-averages which allow us to measure 2D atomic coordinates with up to 0.3 pm precision. Our methods reveal that Se vacancies introduce complex, oscillating strain fields in the WSe$_{2-2x}$Te$_{2x}$ lattice which cannot be explained by continuum elastic theory. These results indicate the potential impact of computer vision for the development of high-precision electron microscopy methods for beam-sensitive materials.
Atomically-precise synthesis and simultaneous integration of 2D transition metal dichalcogenides enabled by nano-confinement
Beijing National Center for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Suzhou Laboratory（苏州实验室）；Institute of Technology for Carbon Neutrality, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences（中国科学院深圳先进技术研究院碳中和技术研究所）；Frontier Institute of Science and Technology, Xi’an Jiaotong University（西安交通大学前沿科学中心）；Department of Engineering Mechanics and Center for Nano and Micro Mechanics, Tsinghua University（清华大学工程力学系微纳力学与微系统教育部重点实验室）；Faculty of Materials Science and Energy Engineering, Shenzhen University of Advanced Technology（深圳先进材料能源学院）
In this paper, we report a novel chemical doping technique to reduce the contact resistance (Rc) of transition metal dichalcogenides (TMDs) - eliminating two major roadblocks (namely, doping and high Rc) towards demonstration of high-performance TMDs field-effect transistors (FETs). By using 1,2 dichloroethane (DCE) as the doping reagent, we demonstrate an active n-type doping density > 2*1019 cm-3 in a few-layer MoS2 film. This enabled us to reduce the Rc value to a record low number of 0.5 kohm*um, which is ~10x lower than the control sample without doping. The corresponding specific contact…
Investigation of the intrinsic hidden spin texture and spin-state segregation in centrosymmetric monolayer dichalcogenide: effectiveness of the electric-field approach
Altermagnetism, Kagome Flat Band, and Weyl Fermion States in Magnetically Intercalated Transition Metal Dichalcogenides
University of Missouri（密苏里大学）；National Cheng Kung University（国立成功大学）；Center for Quantum Frontiers of Research and Technology (QFort)（量子前沿研究与技术中心）；National Center for Theoretical Sciences（国家理论科学中心）
Competing incommensurability, electronic correlations, and superconductivity in a hybrid transition metal dichalcogenide
Weizmann Institute of Science（魏茨曼科学研究所）；University of Hamburg（汉堡大学）；Bar Ilan University（巴伊兰大学）；The Pennsylvania State University（宾夕法尼亚州立大学）；Technion - Israel Institute of Technology（以色列理工学院）；Goethe Universität Frankfurt（法兰克福歌德大学）
The development of low-resistance source/drain contacts to transition metal dichalcogenides (TMDCs) is crucial for the realization of high-performance logic components. In particular, efficient hole contacts are required for the fabrication of p-type transistors with MoS2, a model TMDC. Previous studies have shown that the Fermi level of elemental metals is pinned close to the conduction band of MoS2, thus resulting in large Schottky barrier heights for holes with limited hole injection from the contacts. Here, we show that substoichiometric molybdenum trioxide (MoOx, x<3), a high workfunction…
Interlayer electronic coupling in two-dimensional (2D) materials enables tunable and emergent properties by stacking engineering. However, it also brings significant evolution of electronic structures and attenuation of excitonic effects in 2D semiconductors as exemplified by quickly degrading excitonic photoluminescence and optical nonlinearities in transition metal dichalcogenides when monolayers are stacked into van der Waals structures. Here we report a novel van der Waals crystal, niobium oxide dichloride, featuring a vanishing interlayer electronic coupling and scalable second harmonic g…
Multilayers based on quantum materials (complex oxides, topological insulators, transition-metal dichalcogenides, etc) have enabled the design of devices that could revolutionize microelectronics and optoelectronics. However, heterostructures incorporating quantum materials from different families remain scarce, while they would immensely broaden the range of possible applications. Here we demonstrate the large-scale integration of compounds from two highly-multifunctional families: perovskite oxides and transition-metal dichalcogenides (TMDs). We couple BiFeO$_3$, a room-temperature multiferr…
Pseudo-one dimensional (pseudo-1D) materials are a new-class of materials where atoms are arranged in chain like structures in two-dimensions (2D). Examples include recently discovered black phosphorus, ReS2 and ReSe2 from transition metal dichalcogenides, TiS3 and ZrS3 from transition metal trichalcogenides and most recently GaTe. The presence of structural anisotropy impacts their physical properties and leads to direction dependent light-matter interactions, dichroic optical responses, high mobility channels, and anisotropic thermal conduction. Despite the numerous reports on the vapor phas…
Nano-thick metallic transition metal dichalcogenides such as VS$_{2}$ are essential building blocks for constructing next-generation electronic and energy-storage applications, as well as for exploring unique physical issues associated with the dimensionality effect. However, such 2D layered materials have yet to be achieved through either mechanical exfoliation or bottom-up synthesis. Herein, we report a facile chemical vapor deposition route for direct production of crystalline VS$_{2}$ nanosheets with sub-10 nm thicknesses and domain sizes of tens of micrometers. The obtained nanosheets fea…
Quantum materials are driving a technology revolution in sensing, communication, and computing, while simultaneously testing many core theories of the past century. Materials such as topological insulators, complex oxides, quantum dots, color center hosting semiconductors, and other types of strongly correlated materials can exhibit exotic properties such as edge conductivity, multiferroicity, magnetoresistance, single photon emission, and optical-spin locking. These emergent properties arise and depend strongly on the materials detailed atomic scale structure, including atomic defects, dopant…
Next-generation electronics calls for new materials beyond silicon for increased functionality, performance, and scaling in integrated circuits. Carbon nanotubes and semiconductor nanowires are at the forefront of these materials, but have challenges due to the complex fabrication techniques required for large-scale applications. Two-dimensional (2D) gapless graphene and semiconducting transition metal dichalcogenides (TMDCs) have emerged as promising electronic materials due to their atomic thickness, chemical stability and scalability. Difficulties in the assembly of 2D electronic structures…
Ternary compounds of Transition Metal Dichalcogenides are emerging as an interesting class of crystals with tunable electronic properties, which make them attractive for nano-electronic and optoelectronic applications. Among them, Mo$_x$W$_{1-x}$S$_2$ is one of the most studied alloys, due to the well-known, remarkable features of its binary constituents, MoS$_2$ and WS$_2$. The band-gap of this compound can be modelled varying Mo and W percentages in the sample, and its vibrational modes result from a combination of MoS$_2$ and WS$_2$ phonons. In this work, we report transmission measurements…
