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Li Permeability Increase in Nano-Sized Amorphous Silicon Layers
摘要： Li permeation through nano-sized amorphous Si layers is investigated for temperatures up to 500°C (773 K) as a function of layer thickness between 12 and 95 nm. For the experiments the Si layers are embedded between 6Li and 7Li isotope enriched oxide based Li reservoirs and the thermally induced isotope exchange (through silicon layers and interfaces) is analyzed by Secondary Ion Mass Spectrometry in order to calculate Li permeabilities. The experiments reveal that the interface between silicon and the Li metal oxide does not hinder Li permeation and Li diffusion in silicon controls the overall process. The determined Li permeability increases drastically by orders of magnitude with decreasing silicon layer thickness, accompanied by a decrease in the activation enthalpy of Li permeation. These results can be explained by a gradual transition of trap-limited slow Li diffusion at high silicon thicknesses to interstitial fast Li diffusion at low Si thicknesses.
关键词： Li permeation,nano-sized layers,Li permeability,trap-limited diffusion,amorphous silicon,Secondary Ion Mass Spectrometry,isotope exchange,interstitial diffusion
更新于2025-09-23 15:21:21
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Parallel domain decomposition methods for a quantum-corrected drift–diffusion model for MOSFET devices
摘要： In this paper, we describe parallel domain decomposition methods based on the restricted additive Schwarz (RAS) method for a quantum-corrected drift-diffusion (QCDD) model for MOSFET devices. We have developed hybrid Message Passing Interface (MPI)/OpenMP parallelization algorithms of the QCDD system. For internode parallelization, two extensions of the RAS method are newly developed for the QCDD model. For intranode parallelization, we combine the conjugate gradient (CG) and BiCGSTAB procedures with a splitting-up operator method to realize parallelization of the incomplete factorization. The parallel numerical results for a three-dimensional Si bulk n-MOSFET on a multi-core NEC SX-ACE parallel computer are demonstrated. The intranode parallel numerical results are further evaluated on a many-core Cray XC40 parallel computer.
关键词： Restricted additive Schwarz method,Domain decomposition method,Numerical methods,Device simulation,Semiconductor,quantum-corrected drift–diffusion model
更新于2025-09-23 15:21:21
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<i>(Invited)</i> Proximity Gettering Design of Hydrocarbon Molecular Ion Implanted Silicon Wafers Using Direct Bonding Technique for Advanced CMOS Image Sensors: A Review
摘要： We developed high gettering capability silicon wafers for advanced CMOS image sensors using hydrocarbon molecular ion implantation and surface activated direct wafer bonding (SAB). We found that this novel wafer has three unique characteristics for the improvement of CMOS image sensor device performance. The first is metallic impurity gettering capability in the hydrocarbon ion implantation projection range during CMOS device fabrication. The second is the oxygen out-diffusion barrier effect; this wafer can control out-diffusion to the device active region from the CZ grown silicon substrate during CMOS device heat treatment. The third is the hydrogen passivation effect; hydrogen passivates to the Si/SiO2 gate oxide interface state defects which out-diffuse to the device active region from the hydrocarbon ion implantation projection range during the CMOS device fabrication. Moreover, we demonstrated that this novel wafer can improve the pn-junction leakage current under the actual device fabrication.
关键词： CMOS image sensors,hydrocarbon molecular ion implantation,surface activated direct wafer bonding,gettering capability,oxygen out-diffusion barrier,hydrogen passivation
更新于2025-09-23 15:21:21
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Adaptability analysis of radiative transport diffusion approximation in planar-graded-index media
摘要： To study the applicability of diffusion approximation method, the influence of the optical thickness, scattering albedo, and wall emissivity of the examined medium on the accuracy of the diffusion approximation is analyzed. The accuracy is determined by comparison with results obtained by using the Monte Carlo method. By calculating the dimensionless radiation heat flux distributions at the bottom of the medium for various parameter combinations, the influence of each optical parameter is analyzed. In addition, the adaptability of the diffusion approximation method to the case of a gradient-index medium is examined. The results show that in the homogeneous-refractive-index medium and the gradient-index medium, the accuracy of diffusion approximation method is improved by an increase in the optical thickness or the scattering albedo and by a decrease in the wall emissivity. Moreover, the maximum relative errors are primarily distributed at the medium boundary and center. In the case of increased optical thickness or decreased wall emissivity, the error of the diffusion approximation method becomes stable and remains at a small value.
关键词： numerical analysis,relative error,diffusion approximation,gradient index,Radiative transfer
更新于2025-09-23 15:21:21
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A new diffusion and substitution based cryptosystem for securing medical image applications
摘要： Due to the rising privilege for tele-health facilities have sophisticated responsiveness in the usage of medicinal image safeguard proficiency. It mainly compact with patient records that are secretive and must only available to legal person. So the medical image safety becomes a very significant problem, when patient evidence is conveyed through the public network. In this paper, a secret key of 128-bits size is generated by an image histogram. Initially, the photo sensitive feature of digital imaging and communications in medicine image is decomposed by the mixing process. The resulting image is distributed in key reliant blocks and further, these blocks are passed through key reliant diffusion and substitution processes. A total of five rounds are used in the encryption method. Finally the generated secret key is embedded within the encrypted image in the process of steganography. This also enhances the security of proposed cipher. At the receiver side the secret key was recovered from the embedded image and decryption operation was performed in inverse format. Performance analysis designates that the proposed cipher is more secure.
关键词： substitution,steganography,encryption,diffusion,histogram
更新于2025-09-23 15:21:21
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[ACS Symposium Series] Gels and Other Soft Amorphous Solids Volume 1296 || Probe Diffusion Dynamic Light Scattering of Polymer solutions and Gels
摘要： Probe diffusion dynamic light scattering technique is a powerful to investigate the dynamics of polymer chains in polymer solutions and gels. Not only the local dynamics and/or local viscosity but also the gel point and the post-gel dynamics can be investigated. In this chapter, we discuss (1) a conventional probe diffusion of radical polymerization of poly(N-isopropylacrylamide) (PNIPAM) aqueous system, (2) an in-situ isorefractive probe diffusion of tetra-arm poly(ethylene glycol) (Tetra-PEG) undergoing sol-gel transition via cross-end-coupling, and (3) of PNIPAM radical polymerization. It is demonstrated that the gel point is determined as a function of the reaction conversion, which is a more universal measure than the reaction time. The post-gel dynamics explored by the probe particles illuminates the local dynamics in a “pool” of the sol phase surrounded by a gel network. Furthermore, comparison in dynamics is made between well-controlled uniform networks (Tetra-PEG gels) and randomly cross-linked more heterogeneous networks (PNIPAM gels) the probe size from the viewpoints of dependence and scattering angle dependence.
关键词： gel point,Tetra-PEG,post-gel dynamics,Probe diffusion,PNIPAM,gels,polymer solutions,dynamic light scattering
更新于2025-09-23 15:21:21
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Novel strategy to improve the efficiency roll-off at high luminance and operational lifetime of hybrid white OLEDs via employing an assistant layer with triplet-triplet annihilation up-conversion characteristics
摘要： The efficiency roll-off at high luminance and operational lifetime remain a major challenge before the wide applications of white organic light-emitting diodes (WOLEDs) technology. Here we present a novel strategy to improve the efficiency roll-off at high luminance and operational lifetime by employing an assistant layer with triplet-triplet annihilation (TTA) up-conversion characteristics in emitters. It can be seen that at high luminance, the partial triplet energies in emitters will transfer to the TTA assistant layer and finally lead to the TTA emission, which reduces the exciton quenching at high luminance. Therefore, not only the efficiency roll-off, but also the operational lifetime are greatly improved. The resulting hybrid WOLEDs exhibited the maximum forward-viewing external quantum efficiency and power efficiency of 23.6% and 68.8 lm W?1, and they only dropped to 18.3% and 38.1 lm W?1 at 1000 cd m?2 and 17.1% and 25.9 lm W?1 at 5000 cd m?2, which are significantly higher than 10.5% and 17.9 lm W?1 at 5000 cd m?2 of WOLEDs without TTA assistant layer. Furthermore, the operational half-lifetime of the resulting hybrid WOLEDs also reached 600 hours at the luminance of 1000 cd m?2, which is nearly two-fold longer than that of the reference WOLEDs.
关键词： exciton diffusion,triplet-triplet annihilation up-conversion,Efficiency roll-off,white organic light-emitting diodes,lifetime
更新于2025-09-23 15:21:01
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Sputtered and selenized Sb2Se3 thin-film solar cells with open-circuit voltage exceeding 500??mV
摘要： Antimony selenide (Sb2Se3) is a potential absorber material for environment-friendly and cost-efficient photovoltaics and has achieved considerable progress in recent years. However, the severe open-circuit voltage (Voc) deficit ascribed to the interface and/or bulk defect states has become the main obstacle for further efficiency improvement. In this work, Sb2Se3 absorber layer was prepared by an effective combination reaction involving sputtered and selenized Sb precursor thin films. The self-assembled growth of Sb2Se3 thin films with large crystal grains, benign preferential orientation, and accurate chemical composition were successfully fulfilled under an appropriate thickness of Sb precursor and an optimized selenization scenario. Substrate structured Sb2Se3 thin-film solar cells, a champion device with a power-conversion efficiency of 6.84%, were fabricated. This device is comparable to state-of-the-art ones and represents the highest efficiency of sputtered Sb2Se3 solar cells. Importantly, the high Voc of 504 mV is closely related to the reduced deep level defect density for the Sb2Se3 absorber layer, the passivated interfacial defects for Sb2Se3/CdS heterojunction interface, and the additional heterojunction heat treatment-induced Cd and S inter-diffusion. This significantly improved Voc demonstrates remarkable potential to broaden its scope of applications for Sb2Se3 solar cells.
关键词： Open-circuit voltage,Selenization,Sb2Se3 solar Cell,Elemental inter-diffusion,Sputtering
更新于2025-09-23 15:21:01
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Reviewing and understanding the stability mechanism of halide perovskite solar cells
摘要： Finding sustainable and renewable energy to replace traditional fossil fuel is critical for reducing greenhouse gas emission and avoiding environment pollution. Solar cells that convert energy of sunlight into electricity offer a viable route for solving this issue. At present, halide perovskites are the most potential candidate materials for solar cell with considerable power conversion efficiency, whereas their stability remains a challenge. In this work, we summarize four different key factors that influence the stability of halide perovskites: (a) effect of environmental moisture on the degradation of halide perovskites. The performance of halide perovskite solar cells is reduced due to hydrated crystal hinders the diffusion of photo-generated carriers, which can be solved by materials encapsulation technique; (b) photo-induced instability. Through uncovering the underlying physical mechanism, we note that materials engineering or novel device structure can extend the working life of halide perovskites under continuous light exposure; (c) thermal stability. Halide perovskites are rapidly degraded into PbI2 and volatile substances as heating due to lower formation energy, whereas hybrid perovskite is little changed; (d) electric field effect in the degradation of halide perovskites. The electric field impacts significantly on the carrier separation, changes direction of photo-induced currents and generates switchable photovoltaic effect. For each key factor, we have shown in detail the underlying physical mechanisms and discussed the strategies to overcome this stability difficulty. We expect this review from both theoretical and experimental points of view can be beneficial for development of perovskite solar cell materials and promotes practical applications.
关键词： stability mechanism,ion diffusion,perovskite solar cell
更新于2025-09-23 15:21:01
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[IEEE 2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Lecco, Italy (2019.9.25-2019.9.27)] 2019 25th International Workshop on Thermal Investigations of ICs and Systems (THERMINIC) - Reliability Issues of Mid-Power LEDs
摘要： In diffusion-based molecular communication, information transport is governed by diffusion through a fluid medium. The achievable data rates for these channels are very low compared to the radio-based communication system, since diffusion can be a slow process. To improve the data rate, a novel multiple-input multiple-output (MIMO) design for molecular communication is proposed that utilizes multiple molecular emitters at the transmitter and multiple molecular detectors at the receiver (in RF communication these all correspond to antennas). Using particle-based simulators, the channel's impulse response is obtained and mathematically modeled. These models are then used to determine interlink interference (ILI) and intersymbol interference (ISI). It is assumed that when the receiver has incomplete information regarding the system and the channel state, low complexity symbol detection methods are preferred since the receiver is small and simple. Thus, four detection algorithms are proposed—adaptive thresholding, practical zero forcing with channel models excluding/including the ILI and ISI, and Genie-aided zero forcing. The proposed algorithms are evaluated extensively using numerical and analytical evaluations.
关键词： interference,3-D simulation,symbol detection algorithm,Brownian motion,Molecular communication,multiple-input multiple-output,molecular communication testbed,diffusion
更新于2025-09-23 15:21:01