Topological Defects in Two-Dimensional Crystals: The Stress Buildup and Accumulation

2014 ◽  
Vol 81 (9) ◽  
Author(s):  
Zhigong Song ◽  
Zhiping Xu
Keyword(s):  
Large Scale ◽  
2D Materials ◽  
Topological Defects ◽  
Theory Of Elasticity ◽  
Material Strength ◽  
Two Dimensional ◽  
Out Of Plane ◽  
Mechanical Modulation ◽  
Stress Buildup ◽  
Stress Accumulation

Topological defects (TDs) arise in the growth process of two-dimensional (2D) materials, as well as after-growth heat treatment or irradiation. Our atomistic simulation results show that their mechanical modulation of material properties can be understood qualitatively through the theory of elasticity. We find that the in-plane lattice distortion and stress induced by experimentally characterized pentagon-heptagon (5|7) pairs or pentagon-octagon-pentagon (5|8|5) triplets can be captured by 2D models of dislocations or disclinations, although the out-of-plane distortion of the lattice reduces stress localization. Lineups of these TDs create nonlocal stress accumulation within a range of ∼10 nm. Interestingly, pileups of 5|7 and 5|8|5 defects show contrasting tensile and compressive buildups, which lead to opposite grain size dependence of the material strength. These findings improve our understandings of the mechanical properties of 2D materials with TDs, as well as the lattice perfection in forming large-scale continuous graphene films.

Ultrasensitive broadband photodetectors based on two-dimensional Bi2O2Te films

2021 ◽  
Author(s):  
Pin Tian ◽  
Hongbo Wu ◽  
Libin Tang ◽  
Jinzhong Xiang ◽  
Rongbin Ji ◽  
...  
Keyword(s):  
Large Scale ◽  
2D Materials ◽  
Complementary Metal Oxide Semiconductor ◽  
Cmos Technology ◽  
Photocurrent Density ◽  
Short Wave ◽  
Oxide Semiconductor ◽  
Light Illumination ◽  
Two Dimensional ◽  
Weak Light

Abstract Two-dimensional (2D) materials exhibit many unique optical and electronic properties that are highly desirable for application in optoelectronics. Here, we report the study of photodetector based on 2D Bi2O2Te grown on n-Si substrate. The 2D Bi2O2Te material was transformed from sputtered Bi2Te3 ultrathin film after rapid annealing at 400 ℃ for 10 min in air atmosphere. The photodetector was capable of detecting a broad wavelength from 210 nm to 2.4 μm with excellent responsivity of up to 3x105 and 2x104 AW-1, and detectivity of 4x1015 and 2x1014 Jones at deep ultraviolet (UV) and short-wave infrared (SWIR) under weak light illumination, respectively. The effectiveness of 2D materials in weak light detection was investigated by analysis of the photocurrent density contribution. Importantly, the facile growth process with low annealing temperature would allow direct large-scale integration of the 2D Bi2O2Te materials with complementary metal-oxide–semiconductor (CMOS) technology.

scholarly journals Tunable corrugated patterns in an active nematic sheet

2019 ◽  
Vol 116 (45) ◽  
pp. 22464-22470 ◽  
Author(s):  
Anis Senoussi ◽  
Shunnichi Kashida ◽  
Raphael Voituriez ◽  
Jean-Christophe Galas ◽  
Ananyo Maitra ◽  
...  
Keyword(s):  
Large Scale ◽  
Topological Defects ◽  
Hydrodynamic Theory ◽  
Active Matter ◽  
Free Standing ◽  
Chaotic Flows ◽  
Protein Motors ◽  
Out Of Plane ◽  
Restoring Forces ◽  
Far From Equilibrium

Active matter locally converts chemical energy into mechanical work and, for this reason, it provides new mechanisms of pattern formation. In particular, active nematic fluids made of protein motors and filaments are far-from-equilibrium systems that may exhibit spontaneous motion, leading to actively driven spatiotemporally chaotic states in 2 and 3 dimensions and coherent flows in 3 dimensions (3D). Although these dynamic flows reveal a characteristic length scale resulting from the interplay between active forcing and passive restoring forces, the observation of static and large-scale spatial patterns in active nematic fluids has remained elusive. In this work, we demonstrate that a 3D solution of kinesin motors and microtubule filaments spontaneously forms a 2D free-standing nematic active sheet that actively buckles out of plane into a centimeter-sized periodic corrugated sheet that is stable for several days at low activity. Importantly, the nematic orientational field does not display topological defects in the corrugated state and the wavelength and stability of the corrugations are controlled by the motor concentration, in agreement with a hydrodynamic theory. At higher activities these patterns are transient and chaotic flows are observed at longer times. Our results underline the importance of both passive and active forces in shaping active matter and demonstrate that a spontaneously flowing active fluid can be sculpted into a static material through an active mechanism.

scholarly journals Design and Implementation of Ternary Logic Integrated Circuits by Using Novel Two-Dimensional Materials

2019 ◽  
Vol 9 (20) ◽  
pp. 4212 ◽  
Author(s):  
Mingqiang Huang ◽  
Xingli Wang ◽  
Guangchao Zhao ◽  
Philippe Coquet ◽  
Bengkang Tay
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Large Scale ◽  
2D Materials ◽  
Two Dimensional ◽  
Ternary Logic ◽  
Chip Area ◽  
Logic Devices ◽  
Ripple Carry Adder ◽  
Data Density

With the approaching end of Moore’s Law (that the number of transistors in a dense integrated circuit doubles every two years), the logic data density in modern binary digital integrated circuits can hardly be further improved due to the physical limitation. In this aspect, ternary logic (0, 1, 2) is a promising substitute to binary (0, 1) because of its higher number of logic states. In this work, we carry out a systematical study on the emerging two-dimensional (2D) materials (MoS2 and Black Phosphorus)-based ternary logic from individual ternary logic devices to large scale ternary integrated circuits. Various ternary logic devices, including the standard ternary inverter (STI), negative ternary inverter (NTI), positive ternary inverter (PTI) and especially the ternary decrement cycling inverter (DCI), have been successfully implemented using the 2D materials. Then, by taking advantage of the optimized ternary adder algorithm and the novel ternary cycling inverter, we design a novel ternary ripple-carry adder with great circuitry simplicity. Our design shows about a 50% reduction in the required number of transistors compared to the existing ternary technology. This work paves a new way for the ternary integrated circuits design, and shows potential to fulfill higher logic data density and a smaller chip area in the future.

scholarly journals Large-area integration of two-dimensional materials and their heterostructures by wafer bonding

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Arne Quellmalz ◽  
Xiaojing Wang ◽  
Simon Sawallich ◽  
Burkay Uzlu ◽  
Martin Otto ◽  
...  
Keyword(s):  
Wafer Bonding ◽  
Semiconductor Manufacturing ◽  
Large Scale ◽  
Hexagonal Boron Nitride ◽  
2D Materials ◽  
High Volume ◽  
Two Dimensional ◽  
Wafer Level ◽  
Large Area ◽  
Wide Range

AbstractIntegrating two-dimensional (2D) materials into semiconductor manufacturing lines is essential to exploit their material properties in a wide range of application areas. However, current approaches are not compatible with high-volume manufacturing on wafer level. Here, we report a generic methodology for large-area integration of 2D materials by adhesive wafer bonding. Our approach avoids manual handling and uses equipment, processes, and materials that are readily available in large-scale semiconductor manufacturing lines. We demonstrate the transfer of CVD graphene from copper foils (100-mm diameter) and molybdenum disulfide (MoS2) from SiO2/Si chips (centimeter-sized) to silicon wafers (100-mm diameter). Furthermore, we stack graphene with CVD hexagonal boron nitride and MoS2 layers to heterostructures, and fabricate encapsulated field-effect graphene devices, with high carrier mobilities of up to $$4520\;{\mathrm{cm}}^2{\mathrm{V}}^{ - 1}{\mathrm{s}}^{ - 1}$$ 4520 cm 2 V − 1 s − 1 . Thus, our approach is suited for backend of the line integration of 2D materials on top of integrated circuits, with potential to accelerate progress in electronics, photonics, and sensing.

Exploring the electronic band gap of Janus MoSeO and WSeO monolayers and their heterostructures

2021 ◽  
Author(s):  
On Vo Van ◽  
Khanh Nguyen Duy ◽  
Jonathan Sanchez Guerrero ◽  
Hoat Do Minh
Keyword(s):  
Symmetry Breaking ◽  
Band Gap ◽  
2D Materials ◽  
Two Dimensional ◽  
Plane Symmetry ◽  
Electronic Band ◽  
Out Of Plane ◽  
Electronic Band Gap

Designing new two-dimensional (2D) materials based on Janus structure has drawn great attention due to their novel prop erties induced by the out-of-plane symmetry breaking. In this work, we have...

scholarly journals Cosmic String Wakes and Large-Scale Structure

1988 ◽  
Vol 130 ◽  
pp. 562-562
Author(s):  
A. Stebbins ◽  
S. Veeraraghavan ◽  
R. Brandenberger ◽  
J. Silk ◽  
N. Turok
Keyword(s):  
Galaxy Formation ◽  
Large Scale ◽  
Ambient Medium ◽  
Unit Length ◽  
Long Strings ◽  
Topological Defects ◽  
Two Dimensional ◽  
Order Unity ◽  
The Galaxy ◽  
Redshift Survey

Cosmic Strings are one-dimensional topological defects that may be formed in the early universe during a phase transition, and which may be the source of all inhomogeneities in our universe. Their mass per unit length, μ, gives us a dimensionless parameter, μ6 ≡ 106Gμ/c2, which must be of order unity for strings to seed galaxy formation. Results to date from the ongoing CfA redshift survey suggest that galaxies are distributed on two-dimensional surfaces, whose typical separation is about 50h50−1 Mpc. The loop distribution is unlikely to imprint such large-scale patterns in the galaxy positions so we have examined whether this structure could be caused by infinite strings. Because an infinite string typically moves at a substantial fraction of the speed of light, it will leave behind a very large accretion wake in the ambient medium. Gravitational instablity causes these wakes to continue to accrete matter long after the string has moved elsewhere. These wakes form around the two-dimensional surfaces swept out by the long strings.

scholarly journals Disordered hyperuniformity in two-dimensional amorphous silica

2020 ◽  
Vol 6 (16) ◽  
pp. eaba0826 ◽  
Author(s):  
Yu Zheng ◽  
Lei Liu ◽  
Hanqing Nan ◽  
Zhen-Xiong Shen ◽  
Ge Zhang ◽  
...  
Keyword(s):  
Amorphous Silica ◽  
Density Functional ◽  
Large Scale ◽  
Single Layer ◽  
Topological Defects ◽  
Density Functional Theory Calculations ◽  
Density Fluctuations ◽  
Atomic Scale ◽  
Two Dimensional ◽  
Wave Localization

Disordered hyperuniformity (DHU) is a recently proposed new state of matter, which has been observed in a variety of classical and quantum many-body systems. DHU systems are characterized by vanishing infinite-wavelength normalized density fluctuations and are endowed with unique novel physical properties. Here, we report the discovery of disordered hyperuniformity in atomic-scale two-dimensional materials, i.e., amorphous silica composed of a single layer of atoms, based on spectral-density analysis of high-resolution transmission electron microscopy images. Moreover, we show via large-scale density functional theory calculations that DHU leads to almost complete closure of the electronic bandgap compared to the crystalline counterpart, making the material effectively a metal. This is in contrast to the conventional wisdom that disorder generally diminishes electronic transport and is due to the unique electron wave localization induced by the topological defects in the DHU state.

Anomalous Effect on the Phononic Thermal Conductivity of Silicene Nanoribbon by Hydrogenation

2015 ◽  
Vol 1105 ◽  
pp. 110-114 ◽  
Author(s):  
Emmanuel Dioresma Monterola ◽  
Naomi Tabudlong Paylaga ◽  
Giovanni Jariol Paylaga ◽  
Rolando Viño Bantaculo
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Nanowires ◽  
Large Scale ◽  
Massively Parallel ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Anomalous Effect ◽  
Hydrogenated Silicon ◽  
Out Of Plane

Silicene is a two-dimensional (2D) allotrope of silicon known to have a lower thermal conductivity than graphene; thus, more suitable for thermoelectric applications. This paper investigates the effect of hydrogenation on the thermal conductivity of silicene nanoribbon (SiNR) using equilibrium molecular dynamics (EMD) simulations. The simulations were carried out in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) using a modified Tersoff potential that considers both Si-Si and Si-H interactions. The thermal conductivity of fully hydrogenated silicene nanoribbon (H-SiNR), also known as silicane nanoribbon, was found to be higher than that of pristine SiNR in all the temperatures and dimensions considered here. This anomalous enhancement in the thermal conductivity is similar to that found in hydrogenated silicon nanowires (H-SiNWs). A mechanism for this anomalous effect has been proposed relating the hydrogenation of SiNR with the stiffening and increase of the acoustic out-of-plane flexural (ZA) phonon modes. Also, for both SiNR and H-SiNR, the thermal conductivities generally increase as the dimensions are increased while they generally decrease as the temperatures are increased, in agreement to other reports.

scholarly journals Engineering photonic environments for two-dimensional materials

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Xuezhi Ma ◽  
Nathan Youngblood ◽  
Xiaoze Liu ◽  
Yan Cheng ◽  
Preston Cunha ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
2D Materials ◽  
Research Field ◽  
Chemical Compositions ◽  
Two Dimensional ◽  
Two Dimensional Materials ◽  
Out Of Plane ◽  
Small Device ◽  
Light Matter Interaction ◽  
Three Degrees Of Freedom

AbstractA fascinating photonic platform with a small device scale, fast operating speed, as well as low energy consumption is two-dimensional (2D) materials, thanks to their in-plane crystalline structures and out-of-plane quantum confinement. The key to further advancement in this research field is the ability to modify the optical properties of the 2D materials. The modifications typically come from the materials themselves, for example, altering their chemical compositions. This article reviews a comparably less explored but promising means, through engineering the photonic surroundings. Rather than modifying materials themselves, this means manipulates the dielectric and metallic environments, both uniform and nanostructured, that directly interact with the materials. For 2D materials that are only one or a few atoms thick, the interaction with the environment can be remarkably efficient. This review summarizes the three degrees of freedom of this interaction: weak coupling, strong coupling, and multifunctionality. In addition, it reviews a relatively timing concept of engineering that directly applied to the 2D materials by patterning. Benefiting from the burgeoning development of nanophotonics, the engineering of photonic environments provides a versatile and creative methodology of reshaping light–matter interaction in 2D materials.

scholarly journals Growth, coalescence, and etching of two-dimensional overlayers on metals modulated by near-surface Ar nanobubbles

Nano Research ◽  
2021 ◽  
Author(s):  
Wei Wei ◽  
Jiaqi Pan ◽  
Haiping Lin ◽  
Chanan Euaruksakul ◽  
Zhiyun Li ◽  
...  
Keyword(s):  
Large Scale ◽  
2D Materials ◽  
Growth Front ◽  
Scale Production ◽  
Two Dimensional ◽  
Near Surface ◽  
Substrate Interaction ◽  
Large Scale Production ◽  
Surface Catalysis ◽  
Surface Measurements

AbstractThe synthesis of high-quality ultrathin overlayers is critically dependent on the surface structure of substrates, especially involving the overlayer-substrate interaction. By using in situ surface measurements, we demonstrate that the overlayer-substrate interaction can be tuned by doping near-surface Ar nanobubbles. The interfacial coupling strength significantly decreases with near-surface Ar nanobubbles, accompanying by an “anisotropic to isotropic” growth transformation. On the substrate containing near-surface Ar, the growth front crosses entire surface atomic steps in both uphill and downhill directions with no difference, and thus, the morphology of the two-dimensional (2D) overlayer exhibits a round-shape. Especially, the round-shaped 2D overlayers coalesce seamlessly with a growth acceleration in the approaching direction, which is barely observed in the synthesis of 2D materials. This can be attributed to the immigration lifetime and diffusion rate of growth species, which depends on the overlayer-substrate interaction and the surface catalysis. Furthermore, the “round to hexagon” morphological transition is achieved by etching-regrowth, revealing the inherent growth kinetics under quasi-freestanding conditions. These findings provide a novel promising way to modulate the growth, coalescence, and etching dynamics of 2D materials on solid surfaces by adjusting the strength of overlayer-substrate interaction, which contributes to optimization of large-scale production of 2D material crystals.

Sign in / Sign up

Export Citation Format

Share Document