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Photoelectrochemical activity of CdS/Ag/TiO2 nanorod composites: Degradation of nitrobenzene coupled with the concomitant production of molecular hydrogen
摘要： A new dynamical model is built to describe the process of microwave window breakdown at the vacuum/dielectric interface. In this model, the effects of gas desorption and gas diffusion on breakdown are first taken into account. The evolution of the density of electrons and the neutral gas is analyzed. Particle-in-cell simulations are employed to validate this model, and the agreements of comparisons are favorable. The results show that the density of neutral gas decreases exponentially with the distance away from the dielectric surface. It is concluded that the gas diffusion is the main factor in the density reduction of neutral gas. With the influence of gas ionization, the number of electrons striking the dielectric surface increases. As a result, the gas pressure above the dielectric surface increases rapidly. In addition, the discharge formation time tc of microwave window breakdown decreases exponentially with the gas desorption rate. Besides, tc decreases with the energy of the first crossover point of the secondary electron emission curve when the strength of microwave electric field Erf is small. This dynamical model provides a solution to designing the microwave window.
关键词： gas desorption,microwave window breakdown,gas diffusion,vacuum/dielectric interface,particle-in-cell simulations
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || XTEM observations revealing high diffusivity and Ge segregation in UV laser pulse annealed SiGeO and GeTiO amorphous films
摘要： XTEM observations revealing high diffusivity and Ge segregation in UV laser pulse annealed SiGeO and GeTiO amorphous films
关键词： laser annealing,thin films,nanoparticles,Ge diffusion
更新于2025-09-11 14:15:04
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Postannealed Structural Relaxation and Phase Evolution of Quaternary Alloy BeMgZnO
摘要： The thermal stability of quaternary alloy BeMgZnO was investigated in this study. When a Be0.09Mg0.19Zn0.72O alloy film was annealed, structural relaxation and reconstruction of the film layers were found at 600, 700, and 800 °C. Be atoms were found to gradually diffuse out from the host lattice, and Mg atoms were still maintained. As a result, a mixed-phase alloy containing BeO and MgxZn1?xO was continuously generated. Correspondingly, the bandgap of Be0.09Mg0.19Zn0.72O reduced because of the diffusion of Be atoms. Hence, the thermodynamic solubility of BeO in ZnO and MgO was demonstrated to be relatively low. Additionally, the aging effect caused by a higher annealing temperature is more effective than that caused by a lower annealing temperature for a longer time. Due to the improvement of crystal quality, an MSM interdigital structure photodetector based on the 800 °C annealed sample was fabricated and revealed a strong response to the UV light. Our finding provides a new understanding of the ultrawide bandgap quaternary alloy BeMgZnO and contributes to a significant step toward its practical applications.
关键词： bandgap,photodetector,Be diffusion,BeMgZnO,thermal annealing,structural relaxation
更新于2025-09-11 14:15:04
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Minimally Invasive MR Imaging‐guided Stereotactic Laser Thermal Ablation in Neurosurgical Cases of Pediatric Lesional Epilepsy: A Didactic Step-by-Step Practical Approach
摘要： MR imaging– guided thermal ablation, an alternative to conventional surgery, is a minimally invasive procedure with a decrease in the hospital length of stay and intensive care unit use. This procedure, with converging imaging, clinical, and videotelemetry data, has had early success in selected pediatric neurosurgical patients with intractable epilepsy. Our purpose was to describe the step-by-step approach used in our institution for minimally invasive MR imaging– guided stereotactic laser thermal ablation, along with some of its benefits. Use of fast single-shot T1- and T2-weighted sequences allows a rapid outline of the catheter position, which is followed by a targeted limited higher-resolution T2-weighted sequence for detailed assessment of the lesion margins and adjacent critical structures. In our experience, diffusion-weighted images and T2-weighted images allow fast assessment of the treatment effect and correlate well with the real-time estimate of cell death and posttreatment area of encephalomalacia. We found that contrast imaging did not change the treatment plan or outcome. Therefore, we adopted a tailored fast thermal ablation treatment imaging protocol that relied on short and fast acquisitions, including DWI and single-shot T1- and T2-weighted sequences, and allowed a decrease in imaging acquisition time to approximately 45 to 60 minutes and allowed the addition of these patients to the regular MR imaging schedule without major disruptions to overall patient flow. This new approach allowed the spectrum of surgical intervention in intractable epilepsy to include MR imaging– guided thermal ablation as a prephase I or II alternative. A detailed procedure description was provided, followed by examples of patients we treated.
关键词： MR imaging–guided thermal ablation,intractable epilepsy,single-shot T1- and T2-weighted sequences,diffusion-weighted images,pediatric neurosurgical patients,minimally invasive
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Edge Breakdown Suppression of Avalanche Photodiodes using Zn Diffusion and Selective Area Growth
摘要： Avalanche photodiodes are fabricated and characterized, using a single diffusion fabrication process with the surface patterned by selective area growth prior to diffusion. Raster mapping of the photocurrent near the breakdown voltage is used to characterize the electric field distribution in the multiplication layer. Devices fabricated with the precursor CBrCl3 introduced during selective area epitaxy show a smoother surface morphology and effective edge breakdown suppression, while those fabricated without CBrCl3 have a rougher surface morphology and exhibit evidence of premature edge breakdown at the corners of the device along specific crystal orientations. Comparison of the dark current – voltage curves below breakdown shows a reduction of dark current associated with the use of CBrCl3, as well as with the inclusion of floating guard rings in the device design.
关键词： Diffusion,Materials preparation,Optoelectronic and Photonic sensors,Doping,Semiconductor detectors
更新于2025-09-11 14:15:04
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A DLTS Perspective on Electrically Active Defects in Plated Crystalline Silicon n <sup>+</sup> p Solar Cells
摘要： Laser ablation (LA) has been compared with standard wet etching for contact opening in crystalline silicon n+p solar cells, from a perspective of electrically active defects, assessed by Deep-Level Transient Spectroscopy (DLTS). Copper metallization is employed, including a plated nickel diffusion barrier. It is shown that a hole trap around 0.17 eV above the valence band is systematically present in the depletion region of the junctions, irrespective of the contact opening method. This level could correspond with the substitutional nickel donor level in silicon and indicates that Ni in-diffusion occurs during the contact processing. No clear evidence for the presence of electrically active copper has been found. In addition, two other hole traps H2 and H3, belonging to point defects, have been observed after wet etching and standard LA, while for the highest laser power (hard LA) a broad band develops around 175 K, which is believed to be associated with dislocations, penetrating the p-type base region. Evidence will also be given for the impurity decoration of the dislocations, which enhances their electrical activity.
关键词： Deep-Level Transient Spectroscopy (DLTS),copper metallization,electrically active defects,laser ablation,nickel diffusion barrier,wet etching,crystalline silicon n+p solar cells
更新于2025-09-11 14:15:04
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Interface Engineering in Hybrid Iodide CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> Perovskites Using Lewis Base and Graphene toward High-Performance Solar Cells
摘要： Photovoltaic solar cells based on organic-inorganic hybrid halide perovskites have achieved a substantial breakthrough via advanced interface engineerings. Reports have emphasized that combining the hybrid perovskites with Lewis base and/or graphene can definitely improve the performance through surface trap passivation and band alignment alteration; the underlying mechanisms are not yet fully understood. Here, using density functional theory calculations, we show that upon the formation of CH3NH3PbI3 interfaces with three different Lewis base molecules and graphene, the binding strength with S -donors thiocarbamide and thioacetamide is higher than with O-donor dimethyl sulfoxide, while the interface dipole and work function reduction tend to increase from S -donors to O-donor. We provide evidences of deep trap states elimination in the S -donor perovskite interfaces through the analysis of defect formation on the CH3NH3PbI3(110) surface, and of stability enhancement by estimation of activation barriers for vacancy-mediated iodine atom migrations. These theoretical predictions are in line with the experimental observation of performance enhancement in the perovskites prepared using thiocarbamide.
关键词： Perovskite solar cells,ion diffusion,defect,Lewis base,work function,graphene
更新于2025-09-11 14:15:04
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Edge-plasmon assisted electro-optical modulator
摘要： An efficient electro-optical modulation has been demonstrated here by using an edge-plasmon mode specific for the hybrid plasmonic waveguide. Our approach addresses a major obstacle of the integrated microwave photonics caused by the polarization constraints of both active and passive components. In addition to subwavelength confinement, typical for surface plasmon polaritons, the edge-plasmon modes enable exact matching of the polarization requirements for silicon based input/output grating couplers, waveguides, and electro-optical modulators. A concept of the hybrid waveguide, implemented in a sandwichlike structure, implies a coupling of propagating plasmon modes with a waveguide mode. The vertically arranged sandwich includes a thin layer of epsilon-near-zero material (indium tin oxide) providing an efficient modulation at small length scales. Employed edge plasmons possess a mixed polarization state and can be excited with horizontally polarized waveguide modes. It allows the resulting modulator to work directly with efficient grating couplers and avoid using bulky and lossy polarization converters. A 3D optical model based on Maxwell equations combined with drift-diffusion semiconductor equations is developed. Numerically heavy computations involving the optimization of materials and geometry have been performed. Effective modes, stationary state field distribution, an extinction coefficient, optical losses, and charge transport properties are computed and analyzed. In addition to the polarization matching, the advantages of the proposed model include the compact planar geometry of the silicon waveguide, reduced active electric resistance R and a relatively simple design, attractive for experimental realization.
关键词： polarization constraints,hybrid plasmonic waveguide,drift-diffusion semiconductor equations,electro-optical modulation,edge-plasmon mode,indium tin oxide,epsilon-near-zero material,Maxwell equations
更新于2025-09-11 14:15:04
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Self‐assembly of lipid rafts revealed by fluorescence correlation spectroscopy in living breast cancer cells
摘要： In the study, imaging this polarisation Lipids and proteins in the plasma membrane are laterally heterogeneous and formalised as lipid rafts featuring unique biophysical properties. However, self-assembly mechanism of lipid raft cannot be revealed even its physical properties and components were determined in specific physiological two-photon processes. generalised and fluorescence correlation spectroscopy were used to study the fusion of lipid rafts through the membrane phase and the lateral diffusion of lipids in living breast cancer cells. A self-assembly model of lipid rafts and lipid associated with to phase was membrane demonstrate the lipid sorting ability of lipid rafts in the plasma membrane. The results showed that the increased proportion of slow subdiffusion of GM1-binding cholera toxin B-subunit (CT-B) is accompanied with an increased liquid-ordered domain during the β-estradiol-induced fusion of lipid rafts. And slow subdiffusion of CT-B was vanished with the depletion of lipid rafts. Whereas the dialkylindocarbocyanine (DiIC18) diffusion was not specifically regulated by lipid rafts. This study will open up a new insight for uncovering the self-assembly of lipid rafts in specific pathophysiological processes.
关键词： Lipid rafts,Self-assembly,Membrane phase,Fluorescence correlation spectroscopy,Anomalous diffusion
更新于2025-09-11 14:15:04
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IonMonger: a free and fast planar perovskite solar cell simulator with coupled ion vacancy and charge carrier dynamics
摘要： Details of an open-source planar perovskite solar cell simulator, which includes ion vacancy migration within the perovskite layer coupled to charge carrier transport throughout the perovskite and adjoining transport layers in one dimension, are presented. The model equations are discretised in space using a finite element scheme, and temporal integration of the resulting system of differential algebraic equations is carried out in MATLAB. The user is free to modify device parameters, as well as the incident illumination and applied voltage. Time-varying voltage and/or illumination protocols can be specified, e.g. to simulate current–voltage sweeps, or to track the open-circuit conditions as the illumination is varied. Typical simulations, e.g. current–voltage sweeps, only require computation times of seconds to minutes on a modern personal computer. An example set of hysteretic current–voltage curves is presented.
关键词： Perovskite solar cell,Device simulation,Drift–diffusion,Ion vacancy migration
更新于2025-09-11 14:15:04