- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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ELECTROMAGNETIC FIELD THEORY FOR INVARIANT BEAMS USING SCALAR POTENTIALS
摘要： We present a description of the electromagnetic ?eld for propagation invariant beams using scalar potentials. Fundamental dynamical quantities are obtained: energy density, Poynting vector and Maxwell stress tensor. As an example, all these quantities are explicitly calculated for the Bessel beams, which are invariant beams with circular cylindrical symmetry.
关键词： Poynting vector,scalar potentials,Maxwell stress tensor,propagation invariant beams,Bessel beams,electromagnetic field,energy density
更新于2025-09-09 09:28:46
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15.1: <i>Invited Paper:</i> Bonding Spacer Technologies for Future Foldable LCDs using Ultra-Thin Polyimide Substrates
摘要： We have developed foldable LCD using ultra-thin polyimide substrates and bonding polymer spacer and successfully achieved small curvature of radius less than 2mm. We discuss the bonding spacer can suppress the deformation of plastic substrate and achieve high image quality in bending state.
关键词： Polyimide substrate,Small radius of curvature,Foldable LCD,Bending stress,Bonding spacer,Liquid crystal display
更新于2025-09-09 09:28:46
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Investigation into the room temperature creep-deformation of potassium dihydrogen phosphate crystals using nanoindentation
摘要： It has been a tremendous challenge to manufacture damage-free and smooth surfaces of potassium dihydrogen phosphate (KDP) crystals to meet the requirements of high-energy laser systems. The intrinsic issue is whether a KDP crystal can be plastically deformed so that the material can be removed in a ductile mode during the machining of KDP. This study investigates the room temperature creep-deformation of KDP crystals with the aid of nanoindentation. A stress analysis was carried out to identify the creep mechanism. The results showed that KDP crystals could be plastically deformed at the nano-scale. Dislocation motion is responsible for creep-deformation. Both creep rate and creep depth decrease with decrease in peak force and loading rate. Dislocation nucleation and propagation bring about pop-ins in the load-displacement curves during nanoindentation.
关键词： Dislocation,Potassium dihydrogen phosphate (KDP) crystals,Creep-deformation,Stress
更新于2025-09-09 09:28:46
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Extending the SCOPE model to combine optical reflectance and soil moisture observations for remote sensing of ecosystem functioning under water stress conditions
摘要： A radiative transfer and process-based model, called Soil-Canopy-Observation of Photosynthesis and Energy fluxes (SCOPE), relates remote sensing signals with plant functioning (i.e., photosynthesis and evapotranspiration). Relying on optical remote sensing data, the SCOPE model estimates photosynthesis and evapotranspiration, but these ecosystem-level fluxes may be significantly overestimated if water availability is the primary limiting factor for vegetation. Remedying this shortcoming, additional information from extra sources is needed. In this study, we propose considering water stress in SCOPE by incorporating soil moisture data in the model, besides using satellite optical reflectance observations. A functional link between soil moisture, soil surface resistance, leaf water potential and carboxylation capacity is introduced as an extra element in SCOPE, resulting in a soil moisture integrated version of the model, SCOPE-SM. The modified model simulates additional state variables: (i) vapor pressure (ei), both in the soil pore space and leaf stomata in equilibrium with liquid water potential; (ii) the maximum carboxylation capacity (Vcmax) by a soil moisture dependent stress factor; and (iii) the soil surface resistance (rss) through approximation by a soil moisture dependent hydraulic conductivity. The new approach was evaluated at a Fluxnet site (US-Var) with dominant C3 grasses and covering a wet-to-dry episode from January to August 2004. By using the original SCOPE (version 1.61), we simulated half-hourly time steps of plant functioning via locally measured weather data and time series of Landsat (TM and ETM) imagery. Then, SCOPE-SM was similarly applied to simulate plant functioning for three cases using Landsat imagery: (i) with modeled ei; (ii) with modeled ei and Vcmax; and (iii) with modeled ei, Vcmax, and rss. The outputs of all four simulations were compared to flux tower plant functioning measurements. The results indicate a significant improvement proceeding from the first to the fourth case in which we used both Landsat optical imagery and soil moisture data through SCOPE-SM. Our results show that the combined use of optical reflectance and soil moisture observations has great potential to capture variations of photosynthesis and evapotranspiration during drought episodes. Further, we found that the information contained in soil moisture observations can describe more variations of measured evapotranspiration compared to the information contained in thermal observations.
关键词： SCOPE-SM model,Landsat,Evapotranspiration,Vegetation properties,Water stress,Remote sensing,Soil moisture,Vegetation functioning,Vapor pressure,Photosynthesis,Maximum carboxylation capacity,Soil surface resistance,Reflectance
更新于2025-09-09 09:28:46
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Toward high-contrast AFM-TERS imaging: nano-antenna-mediated remote-excitation on sharp-tip silver nanowire probes
摘要： The tip-enhanced Raman spectroscopy (TERS) imaging technique is designed to provide correlated morphological and chemical information with a nanoscale spatial resolution by utilizing the plasmonic resonance supported by metallic nanostructures at the tip apex of a scanning probe. However, limited by the scattering cross-sections of these nanostructures, only a small fraction of the incident light can be coupled to the plasmonic resonance to generate Raman signals. The uncoupled light then directly excites background spectra with a diffraction-limited resolution, which becomes the background noise that often blurs the TERS image. Here, we demonstrate how this problem can be solved by physically separating the light excitation region from the Raman signal generation region on the scanning probe. The remote-excitation TERS (RE-TERS) probe, which can be fabricated with a facile, robust and reproducible method, utilizes silver nanoparticles as nano-antennas to mediate the coupling of free-space excitation light to propagating surface plasmon polaritons (SPPs) in a sharp-tip silver nanowire to excite Raman signals remotely. With this RE-TERS probe, a 10 nm spatial resolution was demonstrated on a single-walled carbon nanotube (SW-CNT) sample, and the strain distribution in a monolayer molybdenum disulfide (MoS2) was mapped.
关键词： plasmonic antenna,self-assembly,high spatial resolution,Tip-enhanced Raman spectroscopy imaging,stress-mapping,remote-excitation
更新于2025-09-09 09:28:46
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Approximate and explicit expression of optical forces and pull-in instability of a silicon nano-optomechanical device
摘要： Nano-optomechanical systems actuated by optical forces enable many interesting scientific and technological applications. They are vulnerable to the effects of surface stress and Casimir forces. Therefore, calculation of optical forces is essential for the reliability applications of these advanced devices. In this paper, an approximate and explicit expression is developed for the evaluation of the optical force existing between a waveguide and a substrate through the effective refractive index. The influences of surface stress and Casimir forces on the pull-in instability of a silicon nano-optomechanical device actuated by optical forces are investigated. It is found that if neglecting the effect of surface stress, the maximum size, which indicates the device can be safely fabricated, will be over-predicted. The surface stress reduces the critical optical power and its effect is more significant for a slender waveguide.
关键词： surface stress,pull-in instability,Casimir forces,optical force,Nano-optomechanical device
更新于2025-09-09 09:28:46
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Microstructure fabrication process induced modulations in CVD graphene
摘要： The systematic Raman spectroscopic study of a “mimicked” graphene device fabrication is presented. Upon photoresist baking, compressive stress is induced in the graphene which disappears after it is removed. The indirect irradiation from the electron beam (through the photoresist) does not significantly alter graphene characteristic Raman peaks indicating that graphene quality is preserved upon the exposure. The 2D peak shifts and the intensity ratio of 2D and G band, I(2D)/I(G), decreases upon direct metal deposition (Co and Py) suggesting that the electronic modulation occurs due to sp2 C-C bond weakening. In contrast, a thin metal oxide film deposited graphene does not show either the significant 2D and G peaks shift or I(2D)/I(G) decrease upon the metal deposition suggesting the oxide protect the graphene quality in the fabrication process.
关键词： compressive stress,fabrication process,Raman spectroscopy,graphene,metal deposition
更新于2025-09-09 09:28:46
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Development of Auto Infrared Photoelastic Microscope for Stress Measurement of Silicon
摘要： Silicon based materials take a great importance in semiconductor and electronics industries. Detecting the cracks and measuring the stress have become increasingly important for electronic packaging. With knowing of the position and the range of stress concentration and crack zone, people can optimize the arrangement before manufacturing or detect the reliability of devices inworking. We introduce an instrument in this paper which is used to measure both stresses and cracks in silicon based materials for electronic packaging. The instrument was built as a microscope (maximum multiple 20) based on infrared photo elasticity. It was built with the function of automatic rotation of optical devices inside the instrument instead the traditional manual rotation which greatly improved the resolution and stability. A micro heating platform (500 ℃max) can be attached for some experiments with temperature requirement such as TSV temperature cycling test. The resolution of stress-birefringence phase difference is less than 2° (calibrated by the quarter wave plate). It can also be used in Si or SiC wafer bonding quality detection, and stress in MEMS can be measured as well.
关键词： stress,Si-based material,crack,microscope,infrared photo elasticity
更新于2025-09-09 09:28:46
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Improved Negative Bias Stress Stability of Sol-Gel-Processed Mg-Doped In <sub/>2</sub> O <sub/>3</sub> Thin Film Transistors
摘要： We demonstrate sol–gel-processed Mg-doped In2O3 thin film transistors (TFTs) with high performance and improved stability. To improve the performance of indium oxide, which is unstable at a high negative threshold voltage, magnesium is used to suppress oxygen vacancy formation. As the Mg doping concentration increases, the oxygen deficiencies and OH impurities decrease, resulting in a positive shift in the threshold voltage and improved stability in negative bias stress environments. In this experiment, Mg-doped (0 to 2 wt%) indium oxide TFTs are fabricated. Indium oxide prepared from a synthesized solution of an indium nitrate hydrate precursor and 2-methoxyethanol has a mobility of 17.2 cm2/V s. In2O3 TFTs doped with 1 wt% Mg also show a high mobility of 11.02 cm2/V s and a noticeable ?1.5 V threshold voltage shift under negative bias stress. Our results suggest that the sol–gel-processed Mg-doped In2O3 TFTs are a promising candidate for use in high-stability and high-performance applications in transparent devices.
关键词： thin film transistors,negative bias stress,Mg doping,Sol-gel,In2O3
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - Austin, TX, USA (2018.9.24-2018.9.26)] 2018 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD) - A General Approach for Deformation Induced Stress on Flexible Electronics
摘要： We present a simulation approach that is based on non-linear finite element method. This simulation flow allows to calculate large deformation field and associated stress and strain. The obtained simulation result agrees well with analytic solution. We extend this simulation method to evaluate the impacts of the deformation induced stress on device performance as well as structural integrity.
关键词： bending stress,strain,deformation,flexible devices
更新于2025-09-09 09:28:46