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[IEEE 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Kyoto, Japan (2018.7.9-2018.7.13)] 2018 31st International Vacuum Nanoelectronics Conference (IVNC) - Si-Tips with Saturated High Concentration Arsenic Dopant at the Nano-Apexes for Uniform Field Electron Emission
摘要： Both numerical simulation and experimental investigations revealed that the arsenic concentration in the nano-apex of Si tip can reach a saturated high level (i.e., ~6.7×1021 /cm3) through a controllable oxidation process. We take the thermal-induced dopant re-diffusion and self-limitation by the solubility of arsenic in Si into account for the findings. The forming of saturated arsenic concentration at tip-apex could improve the tip-to-tip uniformity of the dopant concentration in an array, and thus enhance the electron emission. Highly reliable gated emitters array (40×40) with typical current density of ~254.53 mA/cm2 (229.08 μA@118.40 V) was demonstrated using Si-tips with saturated dopant concentration.
关键词： tip-to-tip uniformity,gated emitter,saturation of dopant concentration,Si nano-tip
更新于2025-09-23 15:21:21
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Laser Optoacoustic Method for Measurement of Light Extinction Coefficient and Investigation of Its Spatial Distribution in Colloidal Media
摘要： In the present work, the method which allows investigating the spatial distribution of light extinction coefficient in colloidal media is experimentally realized. The proposed method is based on the dependence of temporal profiles of excited OA-signals on the absorption and extinction coefficients of the studied medium. Water-based and kerosene-based magnetic fluids with volume content of magnetite particles in the range 0.35–3.5 % were studied as an example of the medium with spatially non-uniform optical properties. The capability of the reconstruction of the one-dimensional spatial distribution for the light extinction coefficient in the investigated media is demonstrated. It was shown that the relative change of the extinction coefficient with depth depends on volume concentration of magnetite particles, type of acoustical boundary and properties of carrier liquids. In the case of acoustical rigid boundary of magnetic fluid, an additional induced anisotropy occurs, which leads to increasing of the light extinction coefficient with depth in comparison with acoustical free boundary of fluid.
关键词： Laser optoacoustic method,Concentration,Magnetite particles,Thermo-optical excitation,Magnetic fluids,Structural inhomogeneities,Light extinction,Colloidal medium
更新于2025-09-23 15:21:01
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Performance modeling and analysis of high-concentration multi-junction photovoltaics using advanced hybrid cooling systems
摘要： This paper presents the performance modeling and analysis of the high-concentration multi-junction photovoltaic cells, using either constant-width one-section or two-stepwise microchannels-jet impingement hybrid cooling system. The performance simulation and analysis of the cells are conducted using a three dimensional-Computational Fluid Dynamics program for various operating parameters, including water flow rate (100–1300 mL/min.), inlet water temperature (10–80 °C), and heat flux (10–90 W/cm2 corresponding to concentration ratios of 250–2250). The thermal and electrical characteristics of the cells are correlated in dimensionless form as functions of the direct normal irradiance and the operating and geometrical parameters of the hybrid cooling systems. The developed high-quality explicit performance model correlations assist in the design, performance prediction, and selection of operation strategy of photovoltaic cells. The results indicated that the generated and net output power is directly proportional to the applied heat flux (concentration ratio) and inversely proportional to the inlet water temperature. Temperature uniformity of the photovoltaic base enhances with the water flow rate, deteriorates with heat flux, and less affected by the inlet temperature, particularly for the two-sections cooling system. The pumping power increases with water flow rate and decreases as both inlet temperature or heat flux increases. Heat transfer characteristics enhance significantly with water flow rate, moderately with inlet water temperature and slightly with heat flux.
关键词： Photovoltaic performance modeling,High-concentration multi-junction photovoltaic,Operating parameters,Microchannels heat sink,Electrical power correlations
更新于2025-09-23 15:21:01
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Effect of Concentration on the Spectrala??Luminescent Properties of Quantum Dots in Colloidal Solutions
摘要： The effect the concentration of double-shell CdSe/CdS/ZnS semiconductor colloidal quantum dots has on the measured parameters of the absorption and luminescence spectra of a solutions of these quantum dots in toluene is studied via optical spectroscopy. Possible mechanisms of the effect the concentration of quantum dots in the solutions has on the characteristics of the luminescence spectra are analyzed.
关键词： optical spectroscopy,colloidal solutions,concentration,quantum dots,spectral-luminescent properties
更新于2025-09-23 15:21:01
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Laser-Microstructured Copper Reveals Selectivity Patterns in the Electrocatalytic Reduction of CO2
摘要： The local (electro)chemical environment largely influences the selectivity toward, for example, olefins or alcohols in the electroreduction of CO2 over copper (Cu)-based catalysts. However, this factor is mostly qualitatively understood. Here, by combining catalytic results from a set of laser-microstructured Cu electrodes with defined geometries and accurate modeling including bulk and local effects, we map the effect of local pH and CO2 concentration for the main products. We also show how our results are useful for device engineering.
关键词： CO2 electroreduction,CO2 concentration,selectivity patterns,copper catalysts,laser-microstructured electrodes,local pH
更新于2025-09-23 15:21:01
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Oxygen concentration dependence of microstructure formed on Ni by backward pulsed laser deposition
摘要： In the automotive industry, direct joining between resin and metal without additional material is expected due to a growing need for hybrid structures composed of resin and metal. Roughening the metal surface before joining can improve the adhesion with the resin, and forming a microstructure on the metal surface by backward pulsed laser deposition could be a useful method. In the present study, we investigated the dependence of microstructure on the oxygen concentration in the ambient gas during surface processing for controlling the morphology of the microstructure. In the experiments, the oxygen concentration in the ambient gas composed of nitrogen and oxygen was controlled under atmospheric pressure, and microstructure characteristics, such as the shape and hardness, were analyzed. As a result, it was demonstrated that the formation range of the microstructure was constant regardless of the oxygen concentration, whereas a rougher microstructure was formed at higher oxygen concentrations, and a dense, flat microstructure was formed at lower oxygen concentrations. These results implied that the oxidation between the nanoparticles in the laser-induced plume and the ambient gas affects the mobility of the nanoparticles on the metal surface, leading to a transmutation in the morphology of the microstructure. Finally, it was shown that it is important to reduce the surface mobility of nanoparticles, such as processing under high oxygen concentration, to form a microstructure that improves adhesion.
关键词： Resin-metal joining,Backward pulsed laser deposition,Oxygen concentration,Microstructure,Nanosecond pulsed laser
更新于2025-09-23 15:21:01
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THz cutoff frequency and multifunction Ti 2Ba2Ca2Cu3O10/GaAs photonic bandgap materials
摘要： By using the transfer matrix method (TMM), we theoretically explore the transmittance properties and cuto? frequency of one-dimensional photonic crystal (1DPCs) within the terahertz frequency region. The present structure consists of high-temperature superconductor and semiconductor layers. The results of the calculations represent the e?ects of various parameters on the cuto? frequency. We have used the two-?uid model as well as the Drude model to describe the permittivity of superconductor and semiconductor. Further, we consider that the permittivity of both the materials is depending on the hydrostatic pressure. The present results show that with the increasing of di?erent parameters as the operating temperature, the thickness of semiconductor, and the ?lling factor of semiconductor, then the cuto? frequency shift to lower frequencies regions. By the increasing of superconductor thickness, hydrostatic pressure, doping concentration and ?lling factor of the superconductor, we found the cuto? frequency shifts to higher frequency regions. These results indicate that cuto? frequency can be modi?ed through these di?erent parameters. Finally, the present design could be useful for many optical systems as the optical ?lter, re?ector and photoelectronic applications in the Terahertz regime.
关键词： Cuto? frequency,transfer matrix method,photonic crystal,doping concentration,hydrostatic pressure,two-?uid model,Drude model
更新于2025-09-23 15:21:01
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A Novel Inverse Analysis Method to Identify Concentration and Current Density Distributions on Electrode Surface
摘要： A novel method to identify accurate polarization characteristics for a concentration-dependent electrochemical reaction was developed. This method identifies polarization characteristics which are dependent on concentration on electrode surface of a flow cell. Since the concentration on the electrode surface sitting in a flow cell cannot be measured directly, inverse analysis approach is applied. As the observation information of this inverse problem, total currents on the electrode are measured with different bulk concentration. The unknown polarization characteristics are expressed with piecewise linear function with unknown parameters. The relationship between observation and unknown parameters are modeled with advection-diffusion equation. The fluid velocity field of the flow cell is modeled with Navier-Stokes equation. These equations are discretized by finite volume method. In order to validate the proposed method, identification using both numerically generated data and experimental data were performed. The validation result demonstrated the good accuracy of the method.
关键词： inverse analysis,concentration distribution,electrochemical flow cell,current density distribution,polarization characteristics
更新于2025-09-23 15:21:01
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Nonresonant Polarized Raman Spectra Calculations of Nitrogen-Doped Single-Walled Carbon Nanotubes: Diameter, Chirality, and Doping Concentration Effects
摘要： Raman spectra of nitrogen-doped single-walled carbon nanotubes are calculated using the spectral moment’s method combined with the bond polarizability model. The influence of the nanotube diameter and chirality is investigated. We also address the important question of the effect of the N-doping concentration, and we propose an equation to estimate the doping concentration from the knowledge of the tube diameter and the frequency of the radial breathing mode.
关键词： spectral moment’s method,Raman spectra,N-doping concentration,nanotube diameter,nitrogen-doped single-walled carbon nanotubes,bond polarizability model,chirality
更新于2025-09-23 15:21:01
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Quantifying the Oligomeric States of Membrane Proteins in Cells through Super-Resolution Localizations
摘要： Transitions between different oligomeric states of membrane proteins are essential for proper cellular functions. However, the quantification of their oligomeric states in cells is technically challenging. Here we developed a new method to quantify oligomeric state(s) of highly-expressed membrane proteins using the probability density function of molecule density (PDFMD) calculated from super-resolution localizations. We provided the theoretical model of PDFMD, discussed the effects of protein concentration, cell geometry and photophysics of fluorescent proteins on PDFMD, and provided experimental criteria for proper quantification of oligomeric states. This method was further validated using simulated single-molecule fluorescent movies, and applied to two membrane proteins, UhpT and SbmA in E. coli. The study shows that PDFMD is useful in quantifying oligomeric states of membrane proteins in cells that can help in understanding cellular tasks. Potential applications to proteins with higher oligomeric states under high concentration and limitation of our methodology were also discussed.
关键词： PALM,Photophysics,Protein concentration,Cell geometry,Single molecule
更新于2025-09-23 15:21:01