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A highly efficient NiFe nanoparticles decorated Si photoanode for photoelectrochemical water oxidation
摘要： n-Si is a narrow band gap semiconductor that has been demonstrated as an excellent photo-absorber material for photoelectrochemical (PEC) water splitting. Depositing a thin layer of Ni film on n-Si can form a Schottky junction at the interface, which offers a simple and useful route toward light-driven water oxidation. However, the relatively low catalytic activity of the Ni layer and the presence of interface states limits the application of this structure. Herein, we prepared a high performance NiFe nanoparticles decorated Si photoanode for the efficient solar driven water oxidation to H2. NiFe nanoparticles were dispersed on a Si substrate surface homogeneously to form an inhomogeneous metal-insulator-semiconductor (MIS) junction, which increased the photovoltage of photoanode. In addition, the oxide/oxyhydroxide layer on the deposited NiFe layer formed during the evaporation deposition acted as a highly efficient electrocatalyst, which also contributed to the high PEC performance of the photoanode. The photoanode covered with 2 nm NiFe film exhibited the best PEC performance with a low onset potential of 1.09 V vs. RHE (the potential required to reach the photocurrent of 1 mA/cm2), a high photocurrent of 25.2 mA/cm2 at 1.23 V vs. RHE, and a stable output over 50 h under AM 1.5G illumination due to the high performance inhomogeneous MIS junction and a thick oxide/oxyhydroxide catalytic shell formed on NiFe nanoparticle via an aging process.
关键词： photoelectrochemical water oxidation,oxide/oxyhydroxide layer,Si photoanode,NiFe nanoparticles,MIS junction
更新于2025-09-04 15:30:14
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[IEEE 2018 3rd International Conference for Convergence in Technology (I2CT) - Pune (2018.4.6-2018.4.8)] 2018 3rd International Conference for Convergence in Technology (I2CT) - High Frequency Analysis of GaAsP /InSb Hetero-Junction Double Gate Tunnel Field Effect Transistor
摘要： In this paper, we have presented a detailed study on a new Double Gate Tunnel Field-Effect Transistor for suppression of ambipolar behavior and improved high-frequency response. The proposed device Hetero Gate Oxide Hetero-Junction Dual Gate Tunnel Field Effect Transistor (HGO-HJ-DG-TFET) is based on heterojunction material and gate dielectric engineering. Heterojunction provides increment in the drain current (Ids) by decreasing the tunneling width at source-channel (S/C) junction and increase the width at drain-channel (D/C) junction. Further, implementation of high-k dielectric at S/C region helps to increases the electric field thus providing better controllability. Therefore, the proposed device gets better in terms of subthreshold slope, drain current, resistant to parasitic capacitance and high frequency parameters. The reliability of device in high-frequency applications is also studied with optimization of channel length and drain voltage. Hence, the overall performance of the HGO-HJ-DG-TFET is examined using Silvaco TCAD for better efficiency of the device.
关键词： Gate-to-drain capacitance,Band to band tunneling,Hetero junction,Hetero gate oxide
更新于2025-09-04 15:30:14
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FK506 suppresses hypoxia-induced inflammation and protects tight junction function via the CaN-NFATc1 signaling pathway in retinal microvascular epithelial cells
摘要： The present study aimed to identify whether FK506 suppresses hypoxia?induced inflammation and protects tight junction function via the calcineurin-nuclear factor of activated T?cells 1 (CaN?NFATc1) signaling pathway in mouse retinal microvascular endothelial cells (mRMECs). The mRMECs were treated with FK506 at different concentrations following the induction of hypoxia. Trans?epithelial electrical resistance (TEER) and cell permeability were examined to measure the integrity of the tight junctions. The concentrations of inflammatory cytokines were measured using reverse transcription-quantitative polymerase chain reaction analysis and enzyme?linked immunosorbent assays. The protein expression levels of zonula occludens-1 (ZO-1) and nuclear factor of activated T?cell 1 (NFATc1) were identified using immunofluorescent microscopy and western blot analysis. The TEER value was decreased following hypoxia, but increased following treatment with FK506 (1 and 10 μM) for 24 and 48 h. The protein expression of ZO?1 was also increased following FK506 treatment for 24 h at 1 and 10 μM. By contrast, following treatment with FK506 (1 and 10 μM) for 24 and 48 h, the elevated cell permeability in the hypoxia group was significantly downregulated. Similarly, the concentrations of inflammatory cytokines, including cyclooxygenase?2, inducible nitric oxide synthase, monocyte chemoattractant protein-1, interleukin?6, intercellular adhesion molecule?1 and vascular cell adhesion molecule?1, were downregulated following treatment with FK506 for 24 h at 1 and 10 μM. Following treatment with FK506, the level of total NFATc1 was downregulated and the level of phosphorylated NFATc1 was upregulated. Taken together, FK506 suppressed injury to the tight junctions and downregulated the expression of inflammatory cytokines in hypoxia?induced mRMECs via the CaN?NFATc1 signaling pathway. This suggests a potentially effective therapy for hypoxia?induced retinal microangiopathy.
关键词： inflammation,hypoxia,tight junction,calcineurin?nuclear factor of activated T?cells 1 signaling pathway,FK506
更新于2025-09-04 15:30:14
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Model of GaSb-InAs p-i-n Gate All Around (GAA) BioTunnel FET (BTFET)
摘要： The paper investigates the role of hetero-Junction (HJ) p-i-n Gate All Around GAA Tunnel FET architecture for biosensing applications. The device offers better sensitivity and has been modeled in terms of various parameters such as surface potential, threshold voltage and drain current. Analytical modeling scheme relates to the exact resultant solution of two-dimensional Poisson equation. The shift in the threshold voltage has been considered as the sensing parameter to detect the sensitivity when the biomolecules are immobilized in the cavity region.
关键词： Gate all around tunnel FET (GAA-TFET),Model,Bio-Sensor,Hetero Junction (HJ),Dielectric Modulation
更新于2025-09-04 15:30:14
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Quasi-Octave Bandwidth In-Phase Three-Layer Platelet Orthomode Transducer Using Improved Power Combiners
摘要： A 64% instantaneous bandwidth turnstile-junction-based orthomode transducer (OMT) made up of only three layers in a platelet configuration is presented. Such frequency coverage, while maintaining a very much reduced number of layers, is accomplished mainly by incorporating an improved power combiner based on noncontacting matching steps machined in one layer. This solution makes a real impact on the compactness concept of these OMTs while maintaining an excellent electrical performance. An OMT in the 10–20-GHz band was designed and measured by obtaining a return loss of 25 dB, an isolation between rectangular ports of 50 dB, a cross-coupling of 45 dB, and an insertion loss below 0.2 dB.
关键词： waveguide,power combiner,orthomode transducer (OMT),platelet,turnstile junction,Octave bandwidth
更新于2025-09-04 15:30:14
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Lidded vs. Lidless: A Thermal Study
摘要： In the recent years, lidless (bare) die packaging starts to appear in the high power applications with a large die size, complementing the conventional lidded packaging. Given the vast parameters’ space of the lidded vs. lidless designs, a systematic study is necessary to develop a clear and practical design recommendations. In this work, an analytical study is conducted to assess the sensitivity of the thermal spreading resistance (TSR) and the total junction-to-ambient thermal resistance (Rja) on various parameters for a typical lidded (LD) and lidless (LL) package configuration. Useful findings and design guidance are provided.
关键词： junction-to-ambient thermal resistance,lidded packaging,thermal spreading resistance,lidless packaging,thermal management
更新于2025-09-04 15:30:14
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Mg induced compositional change in InGaN alloys
摘要： Tunnel junctions are indispensable elements of multi-junction solar cells. The fabrication of InGaN tunnel junctions requires the growth of degenerately doped n- and p-type layers. While highly doped n-type InGaN films have been demonstrated, the growth of degenerately p-doped InGaN films and the fabrication of high indium fraction InGaN tunnel junctions is still to be demonstrated. We present an investigation of the effect of Mg doping on the InGaN crystal properties over a large range of Mg fluxes and InN mole fractions in the range from 30% to 40%, using multiple characterization techniques. InGaN thin films were grown on GaN/sapphire templates and doped with Mg using plasma assisted molecular beam epitaxy (PAMBE). We have found that the Mg concentration in the film increases linearly with the Mg beam equivalent pressure (BEP) at first, followed by a saturation at ~4x1021 cm-3 similar to the Mg doping behavior reported for GaN. The growth rate of the alloy changes by more than 50% with the changes in the surface availability of Mg. These effects can be explained through the saturation of the atomic sites available for incorporation in the case of Mg concentration saturation and by the passivation of the free nitrogen radicals in the case of the growth rate variation. The incorporation of In and Ga depends on the flux ratio (ΦIn + ΦGa) /(ΦMg) at the growth surface and it is shown that the decrease of this ratio below a threshold of ~2000 causes the almost complete loss of In and the formation of a new quaternary wide band gap semiconductor alloy (InGaMg)N.
关键词： In incorporation,(InGaMg)N alloy,Plasma-assisted molecular beam epitaxy,Tunnel junction,Mg-doped P-type InGaN,InGaN
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Thermal Characterization and Design for a High Density GaN-Based Power Stage
摘要： This paper proposes a methodology for extracting the thermal equivalent circuit of a high density GaN-based power stage, using a 48 V to 12 V GaN-based synchronous buck converter as the test platform. The test setup calculates the junction temperatures by measuring Rds,on for both FETs in the half bridge, while current sources produce power losses in each device and the output filter inductor. Independent control of the two gate voltages allows for either symmetric or asymmetric distribution of power loss between the two FETs, and comparison of these results are used to calculate the coupled and uncoupled thermal resistances between them. The thermal interaction with the filter inductor is similarly modeled. The baseline thermal design with a bare PCB and no heatsink was characterized, as well as a proposed thermal solution consisting of a heatsink, gap pad, gap filler, and a plastic shim. Each configuration was tested with three air flow conditions, and the resulting thermal model was used to estimate the maximum current capability without exceeding 100 °C on either FET. The proposed thermal solution improves the maximum current-handling capability by over 60% compared with the baseline design.
关键词： thermal characterization,eGaN FET,thermal design,HEMT,HFET,heatsink,junction temperature,GaN
更新于2025-09-04 15:30:14