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Device noise reduction for silicon nanowire field-effect-transistor based sensors by using a Schottky junction gate
摘要： The sensitivity of metal-oxide-semiconductor field-effect transistor (MOSFET) based nanoscale sensors is ultimately limited by noise induced by carrier trapping/detrapping processes at the gate oxide/semiconductor interfaces. We have designed a Schottky junction gated silicon nanowire field-effect transistor (SiNW-SJGFET) sensor, where the Schottky junction replaces the noisy oxide/semiconductor interface. Our sensor exhibits significantly reduced device noise, 2.1×10-9 V2μm2/Hz at 1 Hz, compared to reference devices with the oxide/semiconductor interface operated at both inversion and depletion modes. Further improvement can be anticipated by wrapping the nanowire by such a Schottky junction thereby eliminating all oxide/semiconductor interfaces. Hence, a combination of the low-noise SiNW-SJGFET device with a sensing surface of the Nernstian response limit holds promises for future high signal-to-noise ratio sensor applications.
关键词： Noise reduction,field-effect transistor,ion sensor,low frequency noise,schottky junction gate,silicon nanowire
更新于2025-09-23 15:23:52
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Analysis of Thermal and Optical Characteristics of Light Emitting Diode on Various Heatsinks
摘要： Light emitting diodes (LED) are widely used in today’s world due to its less power consumption and its high luminance capacity. Around 20-30% of energy is converted to light energy and 70-80% of energy is dissipated as heat. The excessive rise in temperature causes failure to the LED. An effective thermal management is required for the proper heat dissipation in LED. In this work, the heat dissipation and the optical characteristics of the 16 W LED are studied using different types of aluminium heat sinks. The variation of case and junction temperature as well as the optical characteristic of LED is measured for different heatsink at different It was observed that heat sink with higher surface area shows the best result in terms of lower case and junction temperature. The higher luminous intensity was observed for the parallel fin type 1 heatsink due to higher surface area.
关键词： Heatsink,Case temperature,Light Emitting Diode (LED),Junction temperature
更新于2025-09-23 15:23:52
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Probing interlayer excitons in a vertical van der Waals p-n junction using scanning probe microscopy technique
摘要： Two dimensional (2D) semiconductors feature exceptional optoelectronic properties controlled by strong confinement in one dimension. In this contribution, we studied interlayer excitons in a vertical p-n junction made of bilayer n-type MoS2 and few layers of p-type GaSe using current sensing atomic force microscopy (CSAFM). The p-n interface is prepared by mechanical exfoliation onto highly ordered pyrolytic graphite (HOPG). Thus the heterostructure creates an ideal layered system with HOPG serving as the bottom contact for the electrical characterization. Home-built Au tips are used as the top contact in CSAFM mode. During the basic diode characterization, the p-n interface shows strong rectification behavior with a rectification ratio of 104 at ±1 V. The I-V characteristics reveal pronounced photovoltaic effects with a fill factor of 0.55 by an excitation below the band gap. This phenomenon can be explained by the dissociation of interlayer excitons at the interface. The possibility of the interlayer exciton formation is indicated by density functional theory (DFT) calculations on this heterostructure: the valence band of GaSe and the conduction band of MoS2 contribute to an interface-specific state at an energy of about 1.5 eV. The proof of excitonic transitions to that state is provided by photoluminescence measurements at the p-n interface. Finally, photocurrent mapping at the interface under an excitation wavelength of 785 nm provides evidence of efficient extraction of such excitons. Our results demonstrate a pathway towards a two dimensional device for future optoelectronics and light harvesting assisted by interlayer excitons in a van der Waals heterostructure.
关键词： optoelectronics,van der Waals heterojunction,GaSe,density functional theory,MoS2,interlayer exciton,p-n junction
更新于2025-09-23 15:23:52
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Analysis of a Fractal Josephson Junction with Unharmonic Current-Phase Relation
摘要： In this paper, a fractal Josephson junction with unharmonic current-phase relation is analytically and numerically analyzed. This system has two, four, or no equilibrium points depending on the external direct current source and unharmonic parameter. The stability analysis of the equilibrium points is carried out. The inclusion of unharmonic current-phase relation in an ideal Josephson junction leads to an increase in the hysteresis of current-voltage characteristics. While the inclusion of fractal characteristics in insulating layer of Josephson junction with harmonic current-phase relation leads to a decrease in the hysteresis of current-voltage characteristics. The inclusion of unharmonic current-phase relation on a fractal Josephson junction leads to an increase in the hysteresis of current-voltage characteristics. The dynamical behavior map of fractal Josephson junction with unharmonic current-phase relation in amplitude and frequency of modulation current plane is depicted. For a suitable choice of modulation parameters of external current source, fractal Josephson junction with unharmonic current-phase relation can exhibit excitable mode, bistable oscillatory mode, and periodic and chaotic behaviors.
关键词： Current-voltage characteristics,Unharmonic current-phase relation,Fractal Josephson junction,Bistability,Chaotic behavior,Hysteresis
更新于2025-09-23 15:23:52
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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) - Thermal Analysis on the Degradation of GaN HEMTs
摘要： High temperature operation(HTO) experiments were performed on industrial GaN HEMTs devices. Several degradation failure modes of DC parameters such as transconductance reduction, threshold voltage shift, and gate leakage current increase were identified. The vertical failure localization and analysis of the devices were carried out by electrical method. The results show that the increase of the degradation of the die attach layer is the main reason for the increase of the junction temperature and thermal resistance of the devices. Furthermore, the results are analyzed by three-dimensional X-ray imaging confirming the degradation of the die attach layer. The voids in the die attach layer expanded during the high temperature operation stress experiments, led to a worse heat dissipation performance, which resulting in increased junction temperature, and further accelerate the performance degradation of the devices.
关键词： junction temperature,thermal resistance,reliability,GaN
更新于2025-09-23 15:22:29
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Uncertainty analysis for ac–dc difference measurements with the AC Josephson voltage standard
摘要： A detailed analysis of the uncertainties obtained in ac–dc difference measurements with an AC Josephson voltage standard (ACJVS) is presented. For audio frequencies and for voltages less than 200 mV, ac–dc transfers with the ACJVS may reduce the combined uncertainty by factors of 2–10, compared with conventional methods based on thermal converters. Type A uncertainties are predominantly limited by the thermal transfer standard (TTS), or the digital voltmeter used to acquire the output voltage from the TTS. In agreement with earlier work, the transmission line is the primary contributor to Type B errors for frequencies above 10 kHz. A Monte Carlo sensitivity analysis is used to demonstrate how the uncertainties of transmission line impedance and on-chip inductance impact the accuracy of the rms amplitude conveyed to the TTS.
关键词： ac voltage metrology,transmission line analysis,Josephson junction arrays,quantum voltage standards,uncertainty analysis
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Accurate Building Detection in VHR Remote Sensing Images Using Geometric Saliency
摘要： This paper aims to address the problem of detecting buildings from remote sensing images with very high resolution (VHR). Inspired by the observation that buildings are always more distinguishable in geometries than in texture or spectral, we propose a new geometric building index (GBI) for accurate building detection, which relies on the geometric saliency of building structures. The geometric saliency of buildings is derived from a mid-level geometric representation based on meaningful junctions that can locally describe anisotropic geometrical structures of images. The resulting GBI is measured by integrating the derived geometric saliency of buildings. Experiments on three public datasets demonstrate that the proposed GBI achieves very promising performance, and meanwhile shows impressive generalization capability.
关键词： remote sensing image,geometric saliency,junction,Building detection
更新于2025-09-23 15:22:29
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MoS2/silicon-on-insulator Heterojunction Field-Effect-Transistor for High-performance Photodetection
摘要： In this letter, we demonstrate a novel junction field effect transistor (JFET) by transferring MoS2 onto silicon-on-insulator (SOI) substrate to control the thin Si channel. By combining high light absorption coefficient in MoS2 with high internal gain in thin Si channel, the device can be used for photodetection and achieve high responsivity up to ~1.78×104 A/W, high detectivity over 3×1013 Jones, and short response time down to 1.44 ms. Furthermore, unlike conventional SOI photodetector which is only sensitive to UV light, the response spectrum of our proposed device peaks in visible/near-infrared region, which is interesting for imaging and optical communication applications.
关键词： SOI,High photoresponsivity,Van der Waals heterojunction,MoS2,Junction field effect transistor
更新于2025-09-23 15:22:29
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AgCl/Ag/LaFeO3 heterojunction with a prolonged charge lifetime and enhanced visible light catalytic property
摘要： In this study, uniform mesoporous three–dimensional LaFeO3 with diameter of 2–3 μm was prepared by a hydrothermal process and monodispersed AgCl was then decorated on the surface of the LaFeO3 to form AgCl/Ag/LaFeO3 heterojunction via a facile precipitation–deposition process. The e?ects of the proportions employed in the preparation of the heterojunction on the structural, crystallinity, surface areas, and optical properties of AgCl/Ag/LaFeO3 were systematically studied, which showed that the AgCl/Ag/LaFeO3 heterojunction had a strong hybrid–junction structure, suitable absorption edge, and many exposed surface sites. The AgCl/Ag/LaFeO3 heterojunction had a strong catalytic activity during the degradation of methylene blue and phenol under visible light. The results demonstrated that the AgCl/Ag/LaFeO3 heterojunction had a more intense photocurrent response and smaller surface resistance than both AgCl and LaFeO3. The enhanced photocatalytic ability was attributed to the formation of heterojunctions between AgCl and LaFeO3, which suppressed the recombination of photogenerated electron–hole pairs. Our results may facilitate the rational design of highly e?cient heterogeneous heterojunctions for the removal of organic pollution.
关键词： AgCl/Ag/LaFeO3,Hybrid–junction structure,Charge transfer property,Visible light
更新于2025-09-23 15:22:29
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A New Broadband Magic Tee Design for Ka-Band Satellite Communications
摘要： This letter deals with the design, electromagnetic simulation, and test results of a novel broadband Magic Tee for Ka-band (25.5–27 GHz) satellite communications. Novel matching structure is implemented in the Magic Tee, which results in better electrical performances over broad bandwidth. The designed Magic Tee is realized using electro-discharge machining fabrication technique for achieving stringent dimensional accuracy. The measured bandwidth of the Magic Tee is approximately 16% with a maximum measured in-band insertion loss of 0.2 dB. The simulation results of the developed Magic Tee are compared with measured results using a vector network analyzer showing excellent agreement. The Magic Tee introduced in this letter can be used for designing a monopulse comparator for low earth orbit satellite tracking applications since the amplitude imbalance and phase imbalance of the Magic Tee are negligible, which result in excellent tracking performances.
关键词： Magic Tee junction,monopulse comparator,monopulse tracking,satellite tracking
更新于2025-09-23 15:22:29