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Graphene-Based Nanoscale Vacuum Channel Transistor
摘要： We report the fabrication and electrical performance of nanoscale vacuum channel transistor (NVCT) based on graphene. Ninety-nanometer-width vacuum nano-channel could be precisely fabricated with standard electron beam lithography process. The optimization and treatment of surface damage and adhesive residue on graphene are carried out by ultrasonic cleaning and thermal annealing. Additionally, in situ electric characteristics are directly performed inside a vacuum chamber of scanning electron microscope (SEM) with the nanomanipulator. By modulating the gate voltage, the NVCT could be switched from off-state to on-state, exhibiting an on/off current ratio up to 102 with low working voltages (< 20 V) and leakage current (< 0.5 nA). Furthermore, the nanoscale vacuum channel could enable to scale down the size of vacuum devices with high integration, making NVCT a promising candidate for high speed applications.
关键词： In situ measurement,Graphene,Nanoscale vacuum channel
更新于2025-09-09 09:28:46
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Unveiling the Chemical Composition of Halide Perovskite Films Using Multivariate Statistical Analyses
摘要： The local chemical composition of halide perovskites is a crucial factor in determining their macroscopic properties and their stability. While the combination of scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX) is a powerful and widely used tool for accessing such information, electron-beam-induced damage and complex formulation of the films make this investigation challenging. Here we demonstrate how multivariate analysis – including statistical routines derived from “big data” research, such as Principal Component Analysis, PCA – can be used to dramatically improve the signal recovery from fragile materials. We also show how a similar decomposition algorithm (Non-negative Matrix Factorisation, NMF) can unravel elemental composition at the nanoscale in perovskite films, highlighting the presence of segregated species and identifying the local stoichiometry at the nanoscale.
关键词： hybrid perovskite,big data,multivariate analysis,chemical composition,STEM-EDX,nanoscale
更新于2025-09-09 09:28:46
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Nano Focus: IR vibrational crystallography visualizes molecular orientation on the nanoscale
摘要： The orientation of molecules is of central importance in determining the photophysical properties of organic materials, such as mobility of charge carriers and ions. These orientation-dependent properties of materials further control their functionalities in biological systems and electronic devices, including organic light-emitting diodes and solar cells. Until now, optical crystallography has failed to yield high-resolution images of molecular arrangement, due to the diffraction-limited response, weak photon–material interaction between x-rays and organic materials, or sample damage. A group of researchers from the University of Colorado Boulder and Lawrence Berkeley National Laboratory has developed a new mapping technique called infrared scattering-type scanning near-field optical microscopy (IR s-SNOM), which can identify the molecular arrangement of subdomains smaller than hundreds of nanometers.
关键词： IR vibrational crystallography,IR s-SNOM,organic materials,molecular orientation,nanoscale
更新于2025-09-09 09:28:46
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EFFICIENT ANALYSIS OF ELECTROMAGNETIC FIELDS FOR DESIGNING NANOSCALE ANTENNAS BY USING A BOUNDARY INTEGRAL EQUATION METHOD WITH FAST INVERSE LAPLACE TRANSFORM
摘要： In this paper, we investigate electromagnetic problems for nanoscale antennas by using a boundary integral equation method with fast inverse Laplace transform. The antennas are designed for realizing ultra-fast and high-density magnetic recording. Characteristics of nanoscale antennas are discussed in terms of eigenmodes and time domain responses of electric ?elds. Our computational method is highly e?cient and the computational cost can be reduced by selecting coarse time-step size and performing parallel computation.
关键词： fast inverse Laplace transform,plasmon resonances,nanoscale antennas,electromagnetic fields,boundary integral equation method
更新于2025-09-09 09:28:46
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Nanoscale Metal–Organic Layers for Radiotherapy–Radiodynamic Therapy
摘要： Nanoscale metal?organic layers (nMOLs) are an emerging class of 2D crystalline materials formed by reducing the dimensionality of nanoscale metal?organic frameworks (nMOFs). nMOLs hold significant potential in biomedical applications by combining the structural and compositional tunability of nMOFs and anisotropic properties of 2D nanomaterials. Here we report two novel nMOLs, Hf12-Ir and Hf6-Ir, based on Hf12 and Hf6 secondary building units (SBUs) and photosensitizing Ir(bpy)[dF(CF3)ppy]2+ derived ligands [bpy = 2,2′-bipyridine; dF(CF3)ppy = 2-(2,4-difluorophenyl)-5-(trifluoromethyl)pyridine] for radiotherapy (RT) and radiodynamic therapy (RDT). Upon X-ray irradiation, the Hf12 or Hf6 SBUs in the nMOLs efficiently absorb X-rays to enhance RT by producing hydroxyl radicals and to elicit RDT through the excitation of Ir(bpy)[dF(CF3)ppy]2+ to generate singlet oxygen and superoxide anions. Hf12-Ir and Hf6-Ir promoted effective cell instant death through RDT and reproductive death through RT to elicit superb cell anticancer efficacy, resulting in >99% tumor regression at low X-ray doses of 0.5 × 5 Gy.
关键词： Nanoscale metal?organic layers,Radiodynamic therapy,Radiotherapy,Hf12-Ir,Hf6-Ir
更新于2025-09-09 09:28:46
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Recent Progress in Vacuum Breakdown at Nanoscale: Experiment and Simulation
摘要： Vacuum breakdown at nanoscale are drawing more and more attractions due to the dramatic shrink of the feature size for the vacuum microelectronic devices in space environment and other fields, which demands a further exploring on the fundamental properties of vacuum breakdown at nanoscale. Hence, in the present paper, recent progress on experimental and simulation work are summarized and presented, involving the published work and our research work. The general methodology, typical experimental techniques and the influence factors are all investigated and summarized. Results show that the combination of scanning electron microscope(SEM), focused ion beam and piezoelectric-driven nanomanipulator demonstrates to be an effective and precise technique for the experimental study, which could be used in the range from 10nm to 500nm. Moreover, the factors of electrode materials types, gap distance, electrode geometries play various roles on the vacuum breakdown behaviors as well. In the aspect of simulation research, the analytical solution is found to be the most used method so far. Consequently, the summary of methodology, influence factors and potential mechanism on vacuum breakdown at nanoscale is very vital to help understand the underlying principle and then paves the way to the insulation evaluation and structure design of vacuum micro devices.
关键词： influence factors,vacuum breakdown,mechanism,methodology,nanoscale
更新于2025-09-09 09:28:46
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Encyclopedia of Wireless Networks || Energy Modeling for Nanoscale Terahertz Communication
摘要： Energy modeling for nanoscale terahertz communication is required to investigate the relationship between energy harvesting and consumption in nanoscale terahertz communication and analyze the trade-off between them by jointly considering the constraints of nanonetworks and the peculiarities of terahertz communications, in order to achieve perpetual nanonetworks.
关键词： Energy consumption,Nanoscale communication,Terahertz,Energy harvesting
更新于2025-09-09 09:28:46
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High-fluorescent carbon dots (CDs) originated from China grass carp scales (CGCS) for effective detection of Hg(II) ions
摘要： Carbon dots (CDs) as a kind of environment-friendly fluorescent nanomaterial has been actively studied because of wide and potential applications, such as bioimaging and biosensors. It is worth mentioning that preparing CDs from the recycling of carbonaceous waste has received considerable research interest. We proposed a simple carbon dots synthesis technique, that is, using China grass carp scales (CGCS) as original and green materials by a one-step microwave hydrothermal method to prepare CDs. Since the mercury ion has strongly sulphophile, S atoms display higher thermodynamic affinity and faster integrating process with Hg2+ ions. Due to the presence of large amount of cysteine-containing sulfhydryl groups, the obtained CGCS-CDs can be used as a specific fluorescence probe for detecting Hg2+ ions. Subsequently, CGCS-CDs were characterized by HR-TEM, XRD, FT-IR and XPS analyses. The optical properties of CGCS-CDs were elucidated by fluorescence and UV–vis spectra. Additionally, the effects of pH values and salt concentrations on optical properties of CGCS-CDs were also researched by fluorescence spectra. Under optimal conditions, the decrease of fluorescence intensity displays a good linear relationship with allowable Hg2+ ion detection concentration range of 0.014–30 μmol/L and a limit of detection (LOD) of 0.014 μmol/L is acquired. Meanwhile, the effect of other metal ions on the detection of Hg2+ ions by using CGCS-CDs as fluorescence probe was studied, suggesting that the CGCS-CDs could be an excellent fluorescence probe for the detection of Hg2+ ions. Eventually, the CGCS-CDs were proven to be low toxicity and applied for Hg2+ ions detection in lake water and cosmetic, demonstrating their potential towards diverse applications.
关键词： Sulfhydryl group,Microwave hydrothermal,Nanoscale sensing,Mercury,Carbon dots (CDs),China grass carp scales (CGCS)
更新于2025-09-09 09:28:46
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Imaging the Optical Fields of Functionalized Silver Nanowires through Molecular TERS
摘要： We image 4-mercaptobenzonitrile-functionalized silver nanowires (~20 nm diameter) through tip-enhanced Raman scattering (TERS). The enhanced local optical field-molecular interactions that govern the recorded hyperspectral TERS images are dissected through hybrid finite-difference time-domain-density functional theory simulations. Our forward simulations illustrate that the recorded spatio-spectral profiles of the chemically functionalized nanowires may be reproduced by accounting for the interaction between orientationally averaged molecular polarizability derivative tensors and enhanced incident/scattered local fields polarized along the tip axis. In effect, we directly map the enhanced optical fields of the nanowire in real space through TERS. The simultaneously recorded atomic force microscopy (AFM) images allow a direct comparison between our attainable spatial resolution in topographic (13 nm) and TERS (5 nm) imaging measurements performed under ambient conditions. Overall, our described protocol enables local electric-field imaging with few nm precision through molecular TERS, and it is therefore generally applicable to a variety of plasmonic nano-structures.
关键词： silver nanowires,TERS,nanoscale imaging,optical fields,tip-enhanced Raman scattering
更新于2025-09-09 09:28:46
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Understanding macroscale functionality of metal halide perovskites in terms of nanoscale heterogeneities
摘要： Hybrid metal halide perovskites have shown an unprecedented rise as semiconductor building blocks for solar energy conversion and light-emitting applications. Currently, the field moves empirically towards more and more complex chemical compositions, including mixed halide quadruple cation compounds that allow optical properties to be tuned and show promise for better stability. Despite tremendous progress in the field, there is a need for better understanding of mechanisms of efficiency loss and instabilities to facilitate rational optimization of composition. Starting from the device level and then diving into nanoscale properties, we highlight how structural and compositional heterogeneities affect macroscopic optoelectronic characteristics. Furthermore, we provide an overview of some of the advanced spectroscopy and imaging methods that are used to probe disorder and non-uniformities. A unique feature of hybrid halide perovskite compounds is the propensity for these heterogeneities to evolve in space and time under relatively mild illumination and applied electric fields, such as those found within active devices. This introduces an additional challenge for characterization and calls for application of complimentary probes that can aid in correlating the properties of local disorder with macroscopic function, with the ultimate goal of rationally tailoring synthesis towards optimal structures and compositions.
关键词： halide perovskites,structure-function relationship,nanoscale heterogeneities,recombination
更新于2025-09-09 09:28:46