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Feasibility of three-dimensional reconstruction and automated measurement of fetal long bones using 5D Long Bone
摘要： To evaluate the feasibility of five-dimensional Long Bone (5D LB), a new technique that automatically archives, reconstructs images, and measures lengths of fetal long bones, to assess whether the direction of volume sweep influences fetal long bone measurements in three-dimensional (3D) ultrasound and 5D LB, and to compare measurements of fetal long bone lengths obtained with 5D LB and those obtained with conventional two-dimensional (2D) and manual 3D techniques.
关键词： Fetal biometry,Fetal long bone,Two-dimensional ultrasound,Three-dimensional ultrasound,5D Long Bone
更新于2025-09-19 17:15:36
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Theoretical characterization of hexagonal 2D Be <sub/>3</sub> N <sub/>2</sub> monolayers
摘要： First-principles density functional theory (DFT) calculations are performed to assess the stability, geometric, mechanical, optical and electronic properties of monolayer graphene-like Be3N2. We find that Be3N2 is a large band gap semiconductor with small electron and hole effective masses, which may promote its use in nanoelectronic devices. Furthermore, the excellent thermal, dynamical, and mechanical stability makes it a material of the comparable caliber to that of graphene. In addition, the excellent electrochemical properties of Be3N2 makes it a unique material with the possible theoretical capacities of 974 mAh/g for Li, Na, and K. Moreover, Be3N2 can form bulk graphite-like layered structures with two different configurations, i.e. N2-N1 and N2-Be1. Finally, the derivatives of Be3N2 (Be3N2 nanoribbons) also possess direct band gaps which can finely be tuned to the desired level by geometry and morphology constraints. Based on these fascinating properties, Be3N2 and its derivatives can find a broad range of applications in nanoelectronics and battery technologies.
关键词： DFT calculations,Two-dimensional material,Nano-ribbons,Electrochemical properties,Electronic properties
更新于2025-09-19 17:15:36
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Influence of the support on stabilizing local defects in strained monolayer oxide films
摘要： Two-dimensional materials with a honeycomb lattice, such as graphene and hexagonal boron nitride, often contain local defects in which the hexagonal elements are replaced by four, five, seven, and eight-membered rings. An example is the Stone-Wales (S-W) defect, where a bond rotation causes four hexagons to be transformed into a cluster of two pentagons and two heptagons. A further series of similar defects incorporating divacancies results in larger structures of non-hexagonal elements. In this paper, we use scanning tunneling microscopy (STM) and density functional theory (DFT) modeling to investigate the structure and energetics of S-W and divacancy defects in a honeycomb (2 × 2) Ti2O3 monolayer grown on an Au(111) substrate. The epitaxial rumpled Ti2O3 monolayer is pseudomorphic and in a state of elastic compression. As a consequence, divacancy defects, which induce tension in freestanding films, relieve the compression in the epitaxial Ti2O3 monolayer and therefore have significantly lower energies when compared with their freestanding counterparts. We find that at the divacancy defect sites there is a local reduction of the charge transfer between the film and the substrate, the rumpling is reduced, and the film has an increased separation from the substrate. Our results demonstrate the capacity of the substrate to significantly influence the energetics, and hence favor vacancy-type defects, in compressively strained 2D materials. This approach could be applied more broadly, for example to tensile monolayers, where vacancy-type defects would be rare and interstitial-type defects might be favored.
关键词： elastic strain,local structural defects,monolayers,scanning tunneling microscopy (STM),density functional theory (DFT),two-dimensional materials,ultrathin oxide films
更新于2025-09-19 17:15:36
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Solution-processed ultrathin SnS <sub/>2</sub> -Pt nanoplates for photoelectrochemical water oxidation
摘要： Tin disulfide (SnS2) is attracting significant interest due to the abundance of its elements and its excellent optoelectronic properties in part related to its layered structure. In this work, we detail the preparation of ultrathin SnS2 nanoplates (NPLs) through a hot-injection solution-based process. Subsequently, Pt was grown on their surface via in-situ reduction of a Pt salt. The photoelectrochemical (PEC) performance of such nanoheterostructures as photoanode toward water oxidation was afterward tested. Optimized SnS2-Pt photoanodes provided significantly higher photocurrent densities than bare SnS2 and SnS2-based photoanodes previously reported. Mott-Schottky analysis and PEC impedance spectroscopy (PEIS) were used to analyze in more detail the effect of Pt on the PEC performance. From these analyses, we attribute the enhanced activity of the SnS2-Pt photoanodes here reported to a combination of the very thin SnS2 NPLs and the proper electronic contact between Pt nanoparticles (NPs) and SnS2.
关键词： photoanode,Tin disulfide,SnS2-Pt heterostructure,two-dimensional material,photoelectrochemical water oxidation
更新于2025-09-19 17:15:36
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Fabrication of Two-Dimensional Crystalline Organic Films by Tilted Spin Coating for High-Performance Organic Field-Effect Transistors
摘要： We developed a facile method for fabricating large-area two-dimensional (2D) organic highly crystalline films and extended it to organic thin-film transistor arrays. Tilted spinning provided oriented flow at the three-phase contact line and 2D crystalline film that consisted of layer-by-layer stacked 2,7-diocty[1]benzothieno[3,2-b]benzothiophene (C8-BTBT) was obtained facilely for organic thin-film transistor (OTFT). The extracted field-effect mobility is 4.6 cm-2 V-1 s-1 but with non-ideal features. By applying this method to microdroplet arrays, oriented crystal was fabricated, and the channel region for OTFTs was covered by adjusting the spinning speed. By tuning the tilt angle (θ) of the revolving substrate, we fabricated high-performance OTFT arrays with average and maximum mobilities of 7.5 and 10.1 cm-2 V-1 s-1, respectively, that exhibited high reliability factors of over 90 % and were closed to ideal transistors. These results suggest that high-quality crystalline film can be obtained via a facile tilted spinning method.
关键词： oriented flow,reliability factor,tilted spin coating,two-dimensional,highly crystalline film
更新于2025-09-19 17:15:36
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[IEEE 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Hong Kong, China (2018.11.5-2018.11.9)] 2018 International Conference on Numerical Simulation of Optoelectronic Devices (NUSOD) - Surface Plasmon Polaritons Scattering by Strong Magnetic field in Two-dimensional Material
摘要： Scattering effect of surface plasmon polaritons in two-dimensional material based devices by magnetic fields are analytically studied within the framework of wave optics and plasma model. The theoretical explanation of magnetic scattering and related formulae are provided by considering plasmonic mechanics and solving the equation of motion of electron gas directly. Calculation results illustrating magnetic scattering phenomena are also given by applying an approximation to the first order.
关键词： two-dimensional materials,magnetic fields scattering,analytic methods,surface plasmon polaritons
更新于2025-09-19 17:15:36
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Eighteen functional monolayer metal oxides: wide bandgap semiconductors with superior oxidation resistance and ultrahigh carrier mobility
摘要： Layered metal oxides have emerged as an up-and-comer in the family of two-dimensional materials due to their natural abundance, intrinsic bandgap, and chemical inertness. Based on first-principles calculations, we systematically investigated the atomic structures, energetic stability, and electronic properties of 18 monolayer metal oxides. All these monolayer metal oxides are predicted to be energetically favorable with negative formation energies in the range of -4.27 to -0.47 eV per atom, suggesting good experimental feasibility for synthesis of these monolayer metal oxides. Monolayer metal oxides exhibit superior oxidation resistance, and possess modest to wide bandgaps (1.22–6.48 eV) and high carrier mobility (especially up to 8540 cm2 V?1 s?1 for the InO monolayer), thereby rendering these low-dimensional materials promising candidates for carrier transport. Also, a pronounced in-plane anisotropy for the carrier mobility with a longitudinal/horizontal ratio as large as 115 is revealed for the monolayer metal oxides. These 2D metal oxides exhibit notable absorption in the ultraviolet range with the absorption coefficient >10? cm?1. The combined novel properties of these monolayer metal oxides offer a wide range of opportunities for advanced electronic and optoelectronic applications.
关键词： two-dimensional materials,optoelectronics,monolayer metal oxides,bandgap,carrier mobility,oxidation resistance
更新于2025-09-19 17:15:36
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Embedded two dimensional perovskite nanoplatelets with air-stable luminescence
摘要： Two-dimensional (2D) perovskites represent a class of promising nanostructures for optoelectronic applications owing to their giant oscillator strength transition of excitons and high luminescence. However, major challenges lie in the surface ligand engineering and ambient stability. Here we show that air-stable quasi-2D CsPbBr3 nanoplatelets (NPLs) can be formed in the matrix of Cs4PbBr6 nanosheets by reducing the thickness of Cs4PbBr6 to ~7.6 nm, the scale comparable to the exciton Bohr radius of CsPbBr3. The 2D behavior of excitons is evidenced by the linear increase of radiative lifetime with increasing temperature. Moreover, the wide bandgap Cs4PbBr6 plays roles of surface passivation and protection, which leads to good photoluminescence properties without photo-bleaching effect and with ambient stability for over one month. Our work demonstrates a unique quasi-2D heterostructure of perovskite nanomaterials which may either serve as a workbench for studying the exciton recombination dynamics or find application in high performance optoelectronic devices.
关键词： two dimensional exciton,heterostructure,luminescence,lead halide perovskite
更新于2025-09-19 17:15:36
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Two-Dimensional Hydroxyl-Functionalized and Carbon-Deficient Scandium Carbide, ScC <sub/><i>x</i> </sub> OH, a Direct Bandgap Semiconductor
摘要： Two-dimensional (2D) materials have attracted intensive attention in nanoscience and nanotechnology due to their outstanding properties. Among these materials, the emerging family of 2D transition metal carbides, carbonitrides, and nitrides (referred to as MXenes) stands out because of the vast available chemical space for tuning materials chemistry and surface termination, offering opportunities for property tailoring. Specifically, semiconducting properties are needed to enable utilization in optoelectronics, but direct bandgaps are experimentally challenging to achieve in these 2D carbides. Here, we demonstrate the fabrication of 2D hydroxyl-functionalized and carbon-deficient scandium carbide, namely ScCxOH, by selective etching of a layered parent ScAl3C3 compound. The 2D configuration is determined as a direct bandgap semiconductor, with an experimentally measured bandgap approximated to 2.5 eV. Furthermore, this ScCxOH based device exhibits excellent photoresponse in the ultraviolet-visible light region (responsivity of 0.125 A/W@360 nm/10 V, and quantum efficiency of 43%). Thus, this 2D ScCxOH direct-bandgap semiconductor may find applications in visible-light detectors, photocatalytic chemistry, and optoelectronic devices.
关键词： DFT calculation,photodetector,electronic properties,two-dimensional material,selective etching,MXene
更新于2025-09-19 17:15:36
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Remote Phonon Scattering in Two-Dimensional InSe FETs with High-κ Gate Stack
摘要： This work focuses on the effect of remote phonon arising from the substrate and high-κ gate dielectric on electron mobility in two-dimensional (2D) InSe field-effect transistors (FETs). The electrostatic characteristic under quantum confinement is derived by self-consistently solving the Poisson and Schr?dinger equations using the effective mass approximation. Then mobility is calculated by the Kubo–Greenwood formula accounting for the remote phonon scattering (RPS) as well as the intrinsic phonon scatterings, including the acoustic phonon, homopolar phonon, optical phonon scatterings, and Fr?hlich interaction. Using the above method, the mobility degradation due to remote phonon is comprehensively explored in single- and dual-gate InSe FETs utilizing SiO2, Al2O3, and HfO2 as gate dielectric respectively. We unveil the origin of temperature, inversion density, and thickness dependence of carrier mobility. Simulations indicate that remote phonon and Fr?hlich interaction plays a comparatively major role in determining the electron transport in InSe. Mobility is more severely degraded by remote phonon of HfO2 dielectric than Al2O3 and SiO2 dielectric, which can be effectively insulated by introducing a SiO2 interfacial layer between the high-κ dielectric and InSe. Due to its smaller in-plane and quantization effective masses, mobility begins to increase at higher density as carriers become degenerate, and mobility degradation with a reduced layer number is much stronger in InSe compared with MoS2.
关键词： two-dimensional material,indium selenide,mobility,phonon scattering,high-κ dielectric,field effect transistor
更新于2025-09-19 17:15:36