32 results on '"Xibiao Ren"'
Search Results
2. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering
- Author
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Teng Ma, Zhibo Liu, Jinxiu Wen, Yang Gao, Xibiao Ren, Huanjun Chen, Chuanhong Jin, Xiu-Liang Ma, Ningsheng Xu, Hui-Ming Cheng, and Wencai Ren
- Subjects
Science - Abstract
Understanding the effect of grain boundaries on the electrical and thermal transport properties of graphene is of both fundamental and technological importance. Here, the authors fabricate graphene films with controlled grain size, and determine the scaling laws of thermal and electrical conductivities.
- Published
- 2017
- Full Text
- View/download PDF
3. Formation mechanism of mirror twin grain boundaries in molecular beam epitaxy grown monolayer WSe2–MoSe2 lateral heterojunctions
- Author
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Zhoubin Yu, Yawei Dai, Hannu-Pekka Komsa, Xibiao Ren, Mengfei Yuan, Maohai Xie, and Chuanhong Jin
- Subjects
Mechanics of Materials ,Mechanical Engineering ,General Materials Science ,General Chemistry ,Condensed Matter Physics - Abstract
Mirror twin grain boundary (MTB) defects, being a special type of high-symmetry one-dimensional (1D) defects in two-dimensional atomically thin transition metal dichalcogenides (TMDCs), have received considerable interest due to their unique structures and intriguing 1D properties. However, formation and distribution of MTBs in hybrid TMDC materials such as heterojunction remain scarcely studied. Herein, we investigate the spatial distribution, lattice registry and formation mechanism of MTBs in molecular beam epitaxy grown monolayer WSe2–MoSe2 lateral heterojunctions using atomic-resolution annular dark-field scanning transmission electron microscopy (ADF-STEM). MTBs manifest a much higher density in MoSe2 than in WSe2 domains with a few of them spanning coherently across the domain interface. Compositionally, a Mo-dominant rather than W-dominant configuration was observed in those MTBs located in WSe2 domains and its origin can be attributed to the preferable Mo substitution to W along the MTBs occurring at the later MoSe2 growth period. This proposed mechanism is supported by ab-initio density functional theory calculations and substitution dynamics captured by in-situ ADF-STEM. The present study deepens our understanding of MTBs in heterostructured TMDCs, which may also serve as an excellent platform for the exploration of intriguing 1D physics.
- Published
- 2023
4. Mass transport induced structural evolution and healing of sulfur vacancy lines and Mo chain in monolayer MoS2
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Xiaowei Wang, Chuanhong Jin, Xibiao Ren, Wei Ji, Lin-Fang Hou, and Wei Huang
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Materials science ,Metals and Alloys ,chemistry.chemical_element ,Condensed Matter Physics ,Sulfur ,Adsorption ,chemistry ,Chemical physics ,Lattice (order) ,Desorption ,Vacancy defect ,Monolayer ,Scanning transmission electron microscopy ,Materials Chemistry ,Cluster (physics) ,Physical and Theoretical Chemistry - Abstract
Defects play vital roles in tailoring structures and properties of materials including the atomically thin two-dimensional (2D) materials, and increasing demands are requested to find effective ways to realize the defect engineering, i.e., tuning the defects and thus the materials’ structure–property in a well-controlled way. Herein, we propose a novel method to tune the structures and configurations of one-dimensional (1D) line defects in monolayer MoS2 via mass transport induced structural transformation. By using atomic-resolved annular dark-field scanning transmission electron microscopy (ADF-STEM), we demonstrate in situ that sulfur vacancy line defect can be healed locally into defect-free MoS2 lattice via the desorption of Mo atoms from vacancy lines and adsorption into a moving Mo cluster. Furthermore, directional transport of Mo atoms (or Mo cluster) along the sulfur vacancy lines can induce the formation of Mo chains. Such a mass transport induced defect tuning provides more operational routes for the rational defect designing and property tuning in MoS2 as well as other related 2D materials.
- Published
- 2021
5. Grain Boundary Motion in Two-Dimensional Hexagonal Boron Nitride
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Chuanhong Jin and Xibiao Ren
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Materials science ,Condensed matter physics ,Misorientation ,General Engineering ,General Physics and Astronomy ,Recrystallization (metallurgy) ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic units ,0104 chemical sciences ,Grain growth ,Lattice (order) ,Partial dislocations ,General Materials Science ,Grain boundary ,Crystallite ,0210 nano-technology - Abstract
An in-depth understanding and precise controlling of grain boundary (GB) motion at the atomic scale are crucial for grain growth and recrystallization in polycrystalline materials. So far, the reported studies mainly focus on the GB motion in the ideal bicrystal system, while the atomic mechanisms of GB motion in polycrystals remain poorly understood. Herein, taking two-dimensional (2D) hexagonal boron nitride (h-BN) as a model system, we experimentally investigated the atomic-scale mechanisms of the GB motion in 2D polycrystals. Since GB motion is directly related to the GB structures, this article is organized following the configurations of GBs, which can be divided into straight (including symmetric and asymmetric GBs) and curved GBs. We revealed that (I) for symmetric GBs, the shear-coupled motion alone is insufficient to drive the continuous GB motion in polycrystalline materials, and GB sliding is also needed. (II) For asymmetric GBs, GB motion follows a defaceting-faceting process, in which dislocation reactions are crucial. (III) For curved GBs, shear-coupled GB motion (during grain shrinking) leads to grain rotation, and the rotation direction highly depends on the misorientation angles. (IV) Finally, we will discuss the characteristics of binary lattice h-BN and find that partial dislocations participate in the GB motion at high misorientation angles (>38°). Our results build up the framework of the atomic-scale mechanisms of the GB motion in 2D polycrystalline materials and will be instructive for technological applications such as grain growth and GB engineering.
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- 2020
6. Preparation of Twisted Bilayer Graphene via the Wetting Transfer Method
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JingCun Fan, Wenxiang Wang, Shuai Zhang, Chuanhong Jin, Luqi Liu, Zhaohe Dai, Xibiao Ren, Guorui Wang, Zhong Zhang, Yuan Hou, and YinBo Zhu
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chemistry.chemical_classification ,Materials science ,business.industry ,Capillary action ,Bilayer ,Heterojunction ,02 engineering and technology ,Polymer ,021001 nanoscience & nanotechnology ,01 natural sciences ,symbols.namesake ,chemistry ,0103 physical sciences ,Monolayer ,symbols ,Optoelectronics ,General Materials Science ,Wetting ,van der Waals force ,010306 general physics ,0210 nano-technology ,business ,Bilayer graphene - Abstract
Assembling monolayers into a bilayer system unlocks the rotational free degree of van der Waals (vdW) homo/heterostructure, enabling the building of twisted bilayer graphene (tBLG) which possesses novel electronic, optical, and mechanical properties. Previous methods for preparation of homo/heterstructures inevitably leave the polymer residue or hexagonal boron nitride (h-BN) mask, which usually obstructs the measurement of intrinsic mechanical and surface properties of tBLG. Undoubtedly, to fabricate the designable tBLG with clean interface and surface is necessary but challenging. Here, we propose a simple and handy method to prepare atomically clean twisted bilayer graphene with controllable twist angles based on wetting-induced delamination. This method can transfer tBLG onto a patterned substrate, which offers an excellent platform for the observation of physical phenomena such as relaxation of moire pattern in marginally tBLG. These findings and insight should ultimately guide the designable packaging and atomic characterization of the two-dimensional (2D) materials.
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- 2020
7. Deriving 2D M2X3 (M = Mo, W, X = S, Se) by periodic assembly of chalcogen vacancy lines in their MX2 counterparts
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Xiaowei Wang, Chuanhong Jin, Xibiao Ren, Tian Liu, Xiaoxiao Guan, Juexian Cao, and Wei Huang
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Electron mobility ,Materials science ,02 engineering and technology ,Electron ,021001 nanoscience & nanotechnology ,01 natural sciences ,Molecular physics ,Chalcogen ,Transition metal ,Ab initio quantum chemistry methods ,Lattice (order) ,Vacancy defect ,0103 physical sciences ,Monolayer ,General Materials Science ,010306 general physics ,0210 nano-technology - Abstract
Structural defects in crystals are generally believed to disrupt the symmetry of the pristine lattice, but sometimes, they can also serve as the constituent elements of new structures if they are arranged in a well-ordered pattern. Herein, choosing 2D transition metal dichalcogenides (TMDCs) as a model system, we successfully fabricated a novel group of 2D materials-M2X3 (M = Mo, W, X = S, Se) via the periodic assembly of chalcogen vacancy lines in their corresponding MX2 monolayers (such as MoS2). Our ab initio calculations further revealed that these monolayer M2X3 materials electronically exhibit quasi-direct narrow band-gap semiconducting characteristics, e.g., Eg = 0.89 eV for Mo2S3, and show ultra-high phonon-limited room-temperature carrier mobility up to ∼27 000 cm2 V−1 s−1 for electrons in Mo2S3. The emergence of these novel M2X3 materials expands the existing 2D family and provides new platforms for both fundamental research and practical applications, and the approach via the periodic assembly of ordered defects should also be applicable to other 2D materials.
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- 2020
8. Multifarious Interfaces, Band Alignments, and Formation Asymmetry of WSe2–MoSe2 Heterojunction Grown by Molecular-Beam Epitaxy
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Hongjun Liu, Chuanhong Jin, Xibiao Ren, Wingkin Ho, Xianqi Dai, Maohai Xie, Yawei Dai, Jing Liu, and Junqiu Zhang
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Materials science ,business.industry ,media_common.quotation_subject ,Stacking ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Asymmetry ,0104 chemical sciences ,Image stitching ,Monolayer ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Molecular beam epitaxy ,media_common - Abstract
Monolayer (ML) transition-metal dichalcogenides (TMDs) continue to attract research attention, and the heterojunctions formed by vertically stacking or laterally stitching two different TMDs, e.g.,...
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- 2019
9. Lateral and Vertical MoSe2–MoS2 Heterostructures via Epitaxial Growth: Triggered by High-Temperature Annealing and Precursor Concentration
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Degong Ding, Tao Chen, Xinfeng Liu, Jia Shi, Liangzhi Kou, Guang Wang, Guolin Hao, Xibiao Ren, Xiaoming Zheng, Jianxin Zhong, and Chuanhong Jin
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Materials science ,Annealing (metallurgy) ,business.industry ,Growth kinetics ,Nucleation ,chemistry.chemical_element ,Heterojunction ,02 engineering and technology ,010502 geochemistry & geophysics ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,Sulfur ,chemistry ,Optoelectronics ,General Materials Science ,Physical and Theoretical Chemistry ,0210 nano-technology ,business ,0105 earth and related environmental sciences - Abstract
Atomically thin transition-metal dichalcogenide (TMDC) heterostructures have attracted increasing attention because of their unprecedented potential in the fields of electronics and optoelectronics. However, selective growth of either lateral or vertical TMDC heterostructures remains challenging. Here, we report that lateral and vertical MoS2/MoSe2 epitaxial heterostructures can be successfully fabricated via a one-step growth strategy, which includes triggering by the concentration of sulfur precursor vapor and a high-temperature annealing process. Vertically stacked MoS2/MoSe2 heterostructures can be synthesized via control of the nucleation and growth kinetics, which is induced by high sulfur vapor concentration. The high-temperature annealing process results in the formation of fractured MoSe2 and in situ epitaxial growth of lateral MoSe2-MoS2 heterostructures. This study has revealed the importance of sulfur vapor concentration and high-temperature annealing processes in the controllable growth of MoSe2-MoS2 heterostructures, paving a new route for fabricating two-dimensional TMDC heterostructures.
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- 2019
10. Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2
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Jinhua Hong, Jun Yuan, Guan-Yong Wang, Wei Ji, Maohai Xie, Jin-Feng Jia, Cong Wang, Xibiao Ren, Jinglei Chen, Hongjun Liu, Ze Zhang, and Chuanhong Jin
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Condensed Matter - Materials Science ,Valence (chemistry) ,Condensed matter physics ,Chemistry ,Mechanical Engineering ,Bilayer ,Stacking ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Bioengineering ,Heterojunction ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Brillouin zone ,Condensed Matter::Materials Science ,Lattice (order) ,0103 physical sciences ,Scanning transmission electron microscopy ,General Materials Science ,Density functional theory ,010306 general physics ,0210 nano-technology - Abstract
Interlayer rotation and stacking were recently demonstrated as effective strategies for tuning physical properties of various two-dimensional materials. The latter strategy was mostly realized in hetero-structures with continuously varied stacking orders, which obscure the revelation of the intrinsic role of a certain stacking order in its physical properties. Here, we introduce inversion-domain-boundaries into molecular-beam-epitaxy grown MoSe2 homo-bilayers, which induce unusual-fractional lattice translations to their surrounding domains, accounting for the observed diversity of large-area and uniform stacking sequences. Unusual low-symmetric stacking orders were observed using transmission electron microscopy and detailed geometries were identified by density functional theory. A linear relation was also revealed between interlayer distance and stacking energy. These stacking sequences yield various energy alignments between the valence states at {\Gamma} and K, showing stacking dependent bandgaps and valence band tail states in the measured scanning tunneling spectroscopy. These results may benefit the design of two-dimensional multilayers with manipulable stacking orders., Comment: to be published in Nano Letters
- Published
- 2017
11. Atomic-Precision Fabrication of Quasi-Full-Space Grain Boundaries in Two-Dimensional Hexagonal Boron Nitride
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Xibiao Ren, Xiaowei Wang, and Chuanhong Jin
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Condensed Matter - Materials Science ,Fabrication ,Materials science ,Condensed matter physics ,Mechanical Engineering ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Bioengineering ,Hexagonal boron nitride ,02 engineering and technology ,General Chemistry ,Material Design ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Space (mathematics) ,Faceting ,Partial dislocations ,General Materials Science ,Grain boundary ,0210 nano-technology - Abstract
Precise control and in-depth understanding of the interfaces is crucial for the functionality-oriented material design with desired properties. Herein, via modifying the long-standing bicrystal strategy, we proposed a novel nanowelding approach to build up interfaces between two-dimensional (2D) materials with atomic precision. This method enabled us, for the first time, to experimentally achieve the quasi-full-parameter-space grain boundaries (GBs) in 2D hexagonal boron nitride (h-BN). It further helps us unravel the long-term controversy and confusion on the registry of GBs in h-BN, including i) discriminate the relative contribution of the strain and chemical energy on the registry of GBs; ii) identify a new dislocation core- Frank partial dislocation and four new anti-phase boundaries; and iii) confirm the universal GB faceting. Our work provides a new paradigm to the exploiting of structural-property correlation of interfaces in 2D materials., 49 pages,26 figures
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- 2019
12. Multifarious Interfaces, Band Alignments, and Formation Asymmetry of WSe
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Yawei, Dai, Xibiao, Ren, Junqiu, Zhang, Jing, Liu, Hongjun, Liu, Wingkin, Ho, Xianqi, Dai, Chuanhong, Jin, and Maohai, Xie
- Abstract
Monolayer (ML) transition-metal dichalcogenides (TMDs) continue to attract research attention, and the heterojunctions formed by vertically stacking or laterally stitching two different TMDs, e.g., MoSe
- Published
- 2019
13. Lateral and Vertical MoSe
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Tao, Chen, Degong, Ding, Jia, Shi, Guang, Wang, Liangzhi, Kou, Xiaoming, Zheng, Xibiao, Ren, Xinfeng, Liu, Chuanhong, Jin, Jianxin, Zhong, and Guolin, Hao
- Abstract
Atomically thin transition-metal dichalcogenide (TMDC) heterostructures have attracted increasing attention because of their unprecedented potential in the fields of electronics and optoelectronics. However, selective growth of either lateral or vertical TMDC heterostructures remains challenging. Here, we report that lateral and vertical MoS
- Published
- 2019
14. Small transition-metal dichalcogenide nanostructures down to subnanometer by two-dimensional material origami
- Author
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Bo Wang, Wen Zhao, Xibiao Ren, Feng Ding, Chuanhong Jin, and Wenhui Duan
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Nanotube ,Nanostructure ,Materials science ,Physics and Astronomy (miscellaneous) ,Graphene ,Bent molecular geometry ,Nanotechnology ,02 engineering and technology ,Bending ,021001 nanoscience & nanotechnology ,01 natural sciences ,Nanomaterials ,law.invention ,chemistry.chemical_compound ,Transition metal ,chemistry ,law ,0103 physical sciences ,General Materials Science ,010306 general physics ,0210 nano-technology ,Molybdenum disulfide - Abstract
The large bending stiffnesses of few-atoms-thick two-dimensional (2D) materials doesn't allow them to be bent into nanometer-sized tubes or cages. So, different than graphene, most 2D materials don't have corresponding one-dimensional (1D) nanotube or zero-dimensional (0D) cage structures. In this article, the authors proposed a new strategy to create nanometer-sized 1D or 0D structures of few-atoms-thick 2D materials by using a paper folding-like technique, namely origami approach, to create line defects on one side of the 2D material to induce sharp turns on its surface. Using molybdenum disulfide as an example, their theoretical analysis proved that the origami approach is powerful for creating different types of nanomaterials; some of them are experimentally observed before.
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- 2019
15. Grain Boundaries in Chemical Vapor Deposited Atomically Thin Hexagonal Boron Nitride
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Jidong Li, Chuanhong Jin, Wanlin Guo, Tianru Wu, Ze Zhang, Haomin Wang, Xibiao Ren, Guangyuan Lu, Jichen Dong, Peng Yang, and Feng Ding
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Condensed Matter - Materials Science ,Materials science ,Physics and Astronomy (miscellaneous) ,Wide-bandgap semiconductor ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Heterojunction ,02 engineering and technology ,Chemical vapor deposition ,021001 nanoscience & nanotechnology ,01 natural sciences ,Transmission electron microscopy ,Chemical physics ,0103 physical sciences ,Monolayer ,Ultraviolet light ,General Materials Science ,Grain boundary ,Crystallite ,010306 general physics ,0210 nano-technology - Abstract
Large-area two-dimensional (2D) materials for technical applications can now be produced by chemical vapor deposition (CVD). Unfortunately, grain boundaries (GBs) are ubiquitously introduced as a result of the coalescence of grains with different crystallographic orientations. It is well known that the properties of materials largely depend on GB structures. Here, we carried out a systematic study on the GB structures in CVD-grown polycrystalline h-BN monolayer films by transmission electron microscope. Interestingly, most of these GBs are revealed to be formed via overlapping between neighboring grains, which are distinct from the covalently bonded GBs as commonly observed in other 2D materials. Further density functional theory (DFT) calculations show that the hydrogen plays an essential role in overlapping GB formation. This work provides an in-depth understanding of the microstructures and formation mechanisms of GBs in CVD-grown h-BN films, which should be informative in guiding the precisely controlled synthesis of large area single crystalline h-BN and other 2D materials., 12 pages, 14 figures
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- 2018
16. Growth of Polar Hexagonal Boron Nitride Monolayer on Nonpolar Copper with Unique Orientation
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Jidong Li, Chuanhong Jin, Wanlin Guo, Xiaofei Liu, Jun Yin, Xibiao Ren, and Yao Li
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Materials science ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,Edge (geometry) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Copper ,0104 chemical sciences ,Biomaterials ,Crystallography ,Zigzag ,chemistry ,Monolayer ,Perpendicular ,Polar ,General Materials Science ,Symmetry (geometry) ,0210 nano-technology ,Biotechnology - Abstract
Suppressing the oppositely orientated hexagonal boron nitride (h-BN) domains during the growth is of great challenge due to its bipolar structure. It is found that h-BN domains grown on onefold symmetric Cu(102) or (103) share a unique orientation, with one zigzag edge of the h-BN triangles perpendicular to the symmetry axis of the substrate surface.
- Published
- 2016
17. Exit-wave phase retrieval from a single high-resolution transmission electron microscopy image of a weak-phase object
- Author
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Xibiao Ren, Chuanhong Jin, Feng Lin, H. Li, L.Y. Zhang, Y. Xiao, Q. Zhang, H.T. Xu, and W.P. Zhou
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Materials science ,business.industry ,Graphene ,Phase (waves) ,General Physics and Astronomy ,Hexagonal boron nitride ,02 engineering and technology ,Cell Biology ,021001 nanoscience & nanotechnology ,01 natural sciences ,law.invention ,Optics ,Structural Biology ,Transmission electron microscopy ,law ,Lattice (order) ,0103 physical sciences ,Monolayer ,General Materials Science ,010306 general physics ,0210 nano-technology ,business ,Phase retrieval ,High-resolution transmission electron microscopy - Abstract
We propose a novel algorithm to numerically retrieve the phase of the exit-wave function from a high-resolution transmission electron microscopy (HRTEM) image of a weak-phase object material, e.g., graphene and hexagonal boron nitride monolayers. It theoretically only requires a single HRTEM image to retrieve the phase under the assumption of a weak-phase object. In addition, it can remove the effects of geometrical aberrations up to fifth order, and also improve the degraded information due to the finite temporal and spatial coherence. We further present its applications and successfully demonstrate the identification of the lattice atoms and line defects in single HRTEM image of graphene.
- Published
- 2018
18. Multiple-ellipse fitting method to precisely measure the positions of atomic columns in a transmission electron microscope image
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L.Y. Zhang, X.J. Yue, H.T. Xu, Y. Ouyang, X.J. Wang, Chuanhong Jin, Feng Lin, Xibiao Ren, and Q. Zhang
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010302 applied physics ,Materials science ,business.industry ,General Physics and Astronomy ,02 engineering and technology ,Cell Biology ,021001 nanoscience & nanotechnology ,Ellipse ,01 natural sciences ,Column (database) ,Optics ,Structural Biology ,Transmission electron microscopy ,Position (vector) ,Contour line ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,General Materials Science ,Equidistant ,0210 nano-technology ,business ,High-resolution transmission electron microscopy ,Intensity (heat transfer) - Abstract
In this paper, we propose a multiple-ellipse fitting method to accurately determine the atomic column positions in transmission electron microscopy (TEM) images. The column is enclosed by a series of ellipses fitted from contour lines at equidistant intensity levels, and each atomic column is shaped by an averaged elliptical shape to obtain its positions. In particular, the intensity profile of the atomic column can be obtained by an elliptically rotational average based on its shape; therefore, the intensities of the neighbouring atomic column can be subtracted for each atomic column during subsequent position refinement. This method can achieve precision in the picometre range, and we quantitatively measure this precision by analysing an image containing two Gaussian-shaped atoms and some simulated high-resolution transmission electron microscopy (HRTEM) images of SrTiO3.
- Published
- 2018
19. Three-Leaf Dart-Shaped Single-Crystal BN Formation Promoted by Surface Oxygen
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Chennupati Jagadish, Xibiao Ren, Guo-Ping Guo, Guang-Can Guo, Hui Yang, Chuanhong Jin, Haiyuan Chen, Jin Yang, and Xiaobin Niu
- Subjects
Condensed Matter - Materials Science ,Dart ,Surface oxygen ,Materials science ,Physics and Astronomy (miscellaneous) ,Nucleation ,chemistry.chemical_element ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,02 engineering and technology ,Chemical vapor deposition ,Edge (geometry) ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Oxygen ,0104 chemical sciences ,Crystallography ,chemistry ,0210 nano-technology ,Single crystal ,computer ,FOIL method ,computer.programming_language - Abstract
Two-dimensional hexagonal boron nitride (h-BN) single crystals with various shapes have been synthesized by chemical vapor deposition over the past several years. Here we report the formation of three-leaf dart (3LD)-shaped single crystals of h-BN on Cu foil by atmospheric-pressure chemical vapor deposition. The leaves of the 3LD-shaped h-BN are as long as 18 {\mu}m and their edges are smooth armchair on one side and stepped armchair on the other. Careful analysis revealed that surface oxygen plays an important role in the formation of the 3LD shape. Oxygen suppressed h-BN nucleation by passivating Cu surface active sites and lowered the edge attachment energy, which caused the growth kinetics to change to a diffusion-controlled mode., Comment: 7 pages,6 figures
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- 2018
- Full Text
- View/download PDF
20. All Chemical Vapor Deposition Synthesis and Intrinsic Bandgap Observation of MoS2/Graphene Heterostructures
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Yanfeng Zhang, Shaozhi Deng, Jianping Shi, Chuanhong Jin, Zhongfan Liu, Xiebo Zhou, Mengxi Liu, Yu Zhang, Jinxiu Wen, Huanjun Chen, Donglin Ma, Qingqing Ji, Xibiao Ren, and Ningsheng Xu
- Subjects
Models, Molecular ,Materials science ,Photoluminescence ,Band gap ,Molecular Conformation ,Chemistry Techniques, Synthetic ,Chemical vapor deposition ,law.invention ,law ,Monolayer ,General Materials Science ,Disulfides ,Spectroscopy ,Molybdenum ,business.industry ,Graphene ,Mechanical Engineering ,Temperature ,Heterojunction ,Mechanics of Materials ,Optoelectronics ,Graphite ,Gold ,Volatilization ,Scanning tunneling microscope ,business - Abstract
A facile all-chemical vapor deposition approach is designed, which allows both sequentially grown Gr and monolayer MoS2 in the same growth process, thus allowing the direct construction of MoS2 /Gr vertical heterostructures on Au foils. A weak n-doping effect and an intrinsic bandgap of MoS2 are obtained from MoS2 /Gr/Au via scanning tunneling microscopy and spectroscopy characterization. The exciton binding energy is accurately deduced by combining photoluminescence measurements.
- Published
- 2015
21. Synthesis of in-plane and stacked graphene/hexagonal boron nitride heterostructures by combining with ion beam sputtering deposition and chemical vapor deposition
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Xingwang Zhang, Junhua Meng, Xin Liu, Zhi Gang Yin, Chuanhong Jin, Heng Liu, Hao Lin Wang, and Xibiao Ren
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Range (particle radiation) ,Materials science ,Graphene ,law ,Graphene foam ,General Materials Science ,Nanotechnology ,Heterojunction ,Substrate (electronics) ,Chemical vapor deposition ,Graphene nanoribbons ,Catalysis ,law.invention - Abstract
Graphene/hexagonal boron nitride (h-BN) heterostructures have attracted a great deal of attention in recent years due to their unique and complementary properties for use in a wide range of potential applications. However, it still remains a challenge to synthesize large-area high quality samples by a scalable growth method. In this work, we present the synthesis of both in-plane and stacked graphene/h-BN heterostructures on Cu foils by sequentially depositing h-BN via ion beam sputtering deposition (IBSD) and graphene with chemical vapor deposition (CVD). Due to a significant difference in the growth rate of graphene on h-BN and Cu, the in-plane graphene/h-BN heterostructures were rapidly formed on h-BN domain/Cu substrates. The large-area vertically stacked graphene/h-BN heterostructures were obtained by using the continuous h-BN film as a substrate. Furthermore, the well-designed sub-bilayered h-BN substrates provide direct evidence that the monolayered h-BN on Cu exhibits higher catalytic activity than the bilayered h-BN on Cu. The growth method applied here may have great potential in the scalable preparation of large-area high-quality graphene/h-BN heterostructures.
- Published
- 2015
22. Fabrication of MoSe2 nanoribbons via an unusual morphological phase transition
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Chendong Zhang, Chih-Kang Shih, Yuxuan Chen, Ping Cui, Zhenyu Zhang, Xibiao Ren, and Chuanhong Jin
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Phase transition ,Multidisciplinary ,Fabrication ,Materials science ,Nanostructure ,Condensed matter physics ,Science ,General Physics and Astronomy ,Nanotechnology ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Epitaxy ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,symbols.namesake ,Zigzag ,0103 physical sciences ,symbols ,Nanodot ,van der Waals force ,010306 general physics ,0210 nano-technology ,Molecular beam epitaxy - Abstract
Transition metal dichalcogenides (TMDs) are a family of van der Waals layered materials exhibiting unique electronic, optical, magnetic and transport properties. Their technological potentials hinge critically on the ability to achieve controlled fabrication of desirable nanostructures, such as nanoribbons and nanodots. To date, nanodots/nanoislands have been regularly observed, while controlled fabrication of TMD nanoribbons remains challenging. Here we report a bottom-up fabrication of MoSe2 nanoribbons using molecular beam epitaxy, via an unexpected temperature-induced morphological phase transition from the nanodot to nanoribbon regime. Such nanoribbons are of zigzag nature, characterized by distinct chemical and electronic properties along the edges. The phase space for nanoribbon growth is narrowly defined by proper Se:Mo ratios, as corroborated experimentally using different Se fluxes, and supported theoretically using first-principles calculations that establish the crucial role of the morphological reconstruction of the bare Mo-terminated edge. The growth mechanism revealed should be applicable to other TMD systems. The unique electronic properties of two-dimensional materials are determined not only by their shape, but also the precise atomic arrangement of atoms along edges. Here, Chenet al. have developed a bottom-up epitaxial growth of MoSe2nanoribbons that controls both geometry and edge states.
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- 2017
23. Tailoring the thermal and electrical transport properties of graphene films by grain size engineering
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Huanjun Chen, Teng Ma, Gao Yang, Xibiao Ren, Xiuliang Ma, Ningsheng Xu, Wencai Ren, Jinxiu Wen, Chuanhong Jin, Zhibo Liu, and Hui-Ming Cheng
- Subjects
Materials science ,Science ,Physics::Optics ,General Physics and Astronomy ,Nanotechnology ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,law.invention ,Thermal conductivity ,Electrical resistivity and conductivity ,law ,Thermoelectric effect ,Composite material ,Multidisciplinary ,Graphene ,General Chemistry ,021001 nanoscience & nanotechnology ,Thermoelectric materials ,Grain size ,0104 chemical sciences ,Grain boundary ,0210 nano-technology - Abstract
Understanding the influence of grain boundaries (GBs) on the electrical and thermal transport properties of graphene films is essentially important for electronic, optoelectronic and thermoelectric applications. Here we report a segregation–adsorption chemical vapour deposition method to grow well-stitched high-quality monolayer graphene films with a tunable uniform grain size from ∼200 nm to ∼1 μm, by using a Pt substrate with medium carbon solubility, which enables the determination of the scaling laws of thermal and electrical conductivities as a function of grain size. We found that the thermal conductivity of graphene films dramatically decreases with decreasing grain size by a small thermal boundary conductance of ∼3.8 × 109 W m−2 K−1, while the electrical conductivity slowly decreases with an extraordinarily small GB transport gap of ∼0.01 eV and resistivity of ∼0.3 kΩ μm. Moreover, the changes in both the thermal and electrical conductivities with grain size change are greater than those of typical semiconducting thermoelectric materials., Understanding the effect of grain boundaries on the electrical and thermal transport properties of graphene is of both fundamental and technological importance. Here, the authors fabricate graphene films with controlled grain size, and determine the scaling laws of thermal and electrical conductivities.
- Published
- 2017
24. Fabrication of MoSe
- Author
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Yuxuan, Chen, Ping, Cui, Xibiao, Ren, Chendong, Zhang, Chuanhong, Jin, Zhenyu, Zhang, and Chih-Kang, Shih
- Subjects
Article - Abstract
Transition metal dichalcogenides (TMDs) are a family of van der Waals layered materials exhibiting unique electronic, optical, magnetic and transport properties. Their technological potentials hinge critically on the ability to achieve controlled fabrication of desirable nanostructures, such as nanoribbons and nanodots. To date, nanodots/nanoislands have been regularly observed, while controlled fabrication of TMD nanoribbons remains challenging. Here we report a bottom-up fabrication of MoSe2 nanoribbons using molecular beam epitaxy, via an unexpected temperature-induced morphological phase transition from the nanodot to nanoribbon regime. Such nanoribbons are of zigzag nature, characterized by distinct chemical and electronic properties along the edges. The phase space for nanoribbon growth is narrowly defined by proper Se:Mo ratios, as corroborated experimentally using different Se fluxes, and supported theoretically using first-principles calculations that establish the crucial role of the morphological reconstruction of the bare Mo-terminated edge. The growth mechanism revealed should be applicable to other TMD systems., The unique electronic properties of two-dimensional materials are determined not only by their shape, but also the precise atomic arrangement of atoms along edges. Here, Chen et al. have developed a bottom-up epitaxial growth of MoSe2 nanoribbons that controls both geometry and edge states.
- Published
- 2016
25. Interlayer couplings, Moiré patterns, and 2D electronic superlattices in MoS
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Chendong, Zhang, Chih-Piao, Chuu, Xibiao, Ren, Ming-Yang, Li, Lain-Jong, Li, Chuanhong, Jin, Mei-Yin, Chou, and Chih-Kang, Shih
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Condensed Matter::Materials Science ,2D electronic super-lattices ,Physical Science ,Moire Pattern ,Physics::Optics ,SciAdv r-articles ,van der Waals heterostructures ,Transition metal dichacogenides ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,interlayer coupling ,Research Articles ,Research Article - Abstract
A periodic modulation of the local bandgap in the rotationally aligned MoS2/WSe2 bilayer creates a 2D electronic superlattice., By using direct growth, we create a rotationally aligned MoS2/WSe2 hetero-bilayer as a designer van der Waals heterostructure. With rotational alignment, the lattice mismatch leads to a periodic variation of atomic registry between individual van der Waals layers, exhibiting a Moiré pattern with a well-defined periodicity. By combining scanning tunneling microscopy/spectroscopy, transmission electron microscopy, and first-principles calculations, we investigate interlayer coupling as a function of atomic registry. We quantitatively determine the influence of interlayer coupling on the electronic structure of the hetero-bilayer at different critical points. We show that the direct gap semiconductor concept is retained in the bilayer although the valence and conduction band edges are located at different layers. We further show that the local bandgap is periodically modulated in the X-Y direction with an amplitude of ~0.15 eV, leading to the formation of a two-dimensional electronic superlattice.
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- 2016
26. Low-Temperature Growth of Two-Dimensional Layered Chalcogenide Crystals on Liquid
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Yu Zhou, Yubing Zhou, Bing Deng, Hailin Peng, Chuanhong Jin, Jianbo Yin, Zhongfan Liu, and Xibiao Ren
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Models, Molecular ,Liquid metal ,Materials science ,Chalcogenide ,Nucleation ,Mineralogy ,chemistry.chemical_element ,Bioengineering ,Gallium ,02 engineering and technology ,Chemical vapor deposition ,010402 general chemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Selenium ,law ,General Materials Science ,Crystallization ,business.industry ,Mechanical Engineering ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Surface energy ,0104 chemical sciences ,Cold Temperature ,chemistry ,Optoelectronics ,Chalcogens ,Volatilization ,0210 nano-technology ,business ,Polyimide - Abstract
The growth of high-quality two-dimensional (2D) layered chalcogenide crystals is highly important for practical applications in future electronics, optoelectronics, and photonics. Current route for the synthesis of 2D chalcogenide crystals by vapor deposition method mainly involves an energy intensive high-temperature growth process on solid substrates, often suffering from inhomogeneous nucleation density and grain size distribution. Here, we first demonstrate a facile vapor-phase synthesis of large-area high-quality 2D layered chalcogenide crystals on liquid metal surface with relatively low surface energy at a growth temperature as low as ∼100 °C. Uniform and large-domain-sized 2D crystals of GaSe and GaxIn1-xSe were grown on liquid metal surface even supported on a polyimide film. As-grown 2D GaSe crystals have been fabricated to flexible photodetectors, showing high photoresponse and excellent flexibility. Our strategy of energy-sustainable low-temperature growth on liquid metal surface may open a route to the synthesis of high-quality 2D crystals of Ga-, In-, Bi-, Hg-, Pb-, or Sn-based chalcogenides and halides.
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- 2016
27. Ultrastiff and Strong Graphene Fibers via Full-Scale Synergetic Defect Engineering
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Yang Xu, Chao Gao, Peng Xu, Miao Wang, Li Peng, Xiaoli Zhao, Haiyan Sun, Zhen Xu, Xibiao Ren, Yingjun Liu, and Chuanhong Jin
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Materials science ,Graphene ,business.industry ,Mechanical Engineering ,Full scale ,Oxide ,Defect engineering ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Liquid crystal ,law ,Electrical resistivity and conductivity ,Microelectronics ,General Materials Science ,Composite material ,0210 nano-technology ,business - Abstract
Kilometer-scale continuous graphene fibers (GFs) with outstanding mechanical properties and excellent electrical conductivity are produced by high-throughput wet-spinning of graphene oxide liquid crystals followed by graphitization through a full-scale synergetic defect-engineering strategy. GFs with superior performances promise wide applications in functional textiles, lightweight motors, microelectronic devices, and so on.
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- 2015
28. Hole doping in epitaxial MoSe 2 monolayer by nitrogen plasma treatment
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Maohai Xie, Junqiu Zhang, Bo Wang, Bin Li, Hu Xu, Hao Tian, Xibiao Ren, Chuanhong Jin, Yipu Xia, Jin-Peng Xu, Yue Feng, Wingkin Ho, and Chang Liu
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Materials science ,Condensed matter physics ,Photoemission spectroscopy ,Mechanical Engineering ,Electron energy loss spectroscopy ,Doping ,Scanning tunneling spectroscopy ,technology, industry, and agriculture ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,X-ray photoelectron spectroscopy ,Mechanics of Materials ,0103 physical sciences ,Scanning transmission electron microscopy ,Monolayer ,General Materials Science ,010306 general physics ,0210 nano-technology ,Spectroscopy - Abstract
Many transition-metal dichalcogenides, such as MoSe2, are direct-gap semiconductors at monolayer thickness, which hold potentials in nano-electronics, optoelectronics, and some new concept spin- and valley-electronic applications. For device application, however, controllable doping of the materials is essential. Here we report hole doping of epitaxial MoSe2 by nitrogen (N) plasma treatment with the aim of understanding the defect structure and its electronic characteristics. Examinations by annular dark field scanning transmission electron microscopy clearly reveal substitutional doping of N by replacing Se atoms in MoSe2 monolayer upon N-plasma treatment, though creation of Se vacancies are also possible. Interestingly, we note an unexpectedly high concentration of 'dual defects', where both Se atoms in the top and bottom Se layers of MoSe2 at the same lattice site are substituted by N and/or become vacant, suggesting a catalytic effect of defect formation. X-ray photoelectron spectroscopy and electron energy loss spectroscopy confirm the presence of N–Mo bonds. Photoemission spectroscopy reveals an impurity band as well as the Fermi level shift, confirming the p-type doping effect in MoSe2 monolayer by N-plasma treatment. Consistent with the PES results, scanning tunneling spectroscopy measurement also reveal defect states peaked at 0.6–0.7 eV above the valance band maximum. The effectiveness of N-doping is discussed.
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- 2018
29. Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2.
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Jinhua Hong, Cong Wang, Hongjun Liu, Xibiao Ren, Jinglei Chen, Guanyong Wang, Jinfeng Jia, Maohai Xie, Chuanhong Jin, Wei Ji, Jun Yuan, and Ze Zhang
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- 2017
- Full Text
- View/download PDF
30. Low-Temperature Growth of Two-Dimensional Layered Chalcogenide Crystals on Liquid.
- Author
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Yubing Zhou, Bing Deng, Yu Zhou, Xibiao Ren, Jianbo Yin, Chuanhong Jin, Zhongfan Liu, and Hailin Peng
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- 2016
- Full Text
- View/download PDF
31. Hole doping in epitaxial MoSe2 monolayer by nitrogen plasma treatment.
- Author
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Yipu Xia, Bo Wang, Junqiu Zhang, Yue Feng, Bin Li, Xibiao Ren, Hao Tian, Jinpeng Xu, Wingkin Ho, Hu Xu, Chang Liu, Chuanhong Jin, and Maohai Xie
- Published
- 2018
- Full Text
- View/download PDF
32. Inversion Domain Boundary Induced Stacking and Bandstructure Diversity in Bilayer MoSe2.
- Author
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Jinhua Hong, Cong Wang, Hongjun Liu, Xibiao Ren, Jinglei Chen, Guanyong Wang, Jinfeng Jia, Maohai Xie, Chuanhong Jin, Wei Ji, Jun Yuan, and Ze Zhang
- Subjects
- *
BILAYERS (Solid state physics) , *ELECTRONIC band structure , *TWO-dimensional materials (Nanotechnology) , *MOLYBDENUM compounds , *TRANSMISSION electron microscopy , *MOLECULAR beam epitaxy - Abstract
Interlayer rotation and stacking were recently demonstrated as effective strategies for tuning physical properties of various two-dimensional materials. The latter strategy was mostly realized in heterostructures with continuously varied stacking orders, which obscure the revelation of the intrinsic role of a certain stacking order in its physical properties. Here, we introduce inversion-domain-boundaries into molecular-beam-epitaxy grown MoSe2 homobilayers, which induce uncommon fractional lattice translations to their surrounding domains, accounting for the observed diversity of large-area and uniform stacking sequences. Low-symmetry stacking orders were observed using scanning transmission electron microscopy and detailed geometries were identified by density functional theory. A linear relation was also revealed between interlayer distance and stacking energy. These stacking sequences yield various energy alignments between the valence states at the Γ and K points of the Brillouin zone, showing stacking-dependent bandgaps and valence band tail states in the measured scanning tunneling spectroscopy. These results may benefit the design of two-dimensional multilayers with manipulable stacking orders. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
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