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- 实验方案
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Wave-optics uncertainty propagation and regression-based bias model in GNSS radio occultation bending angle retrievals
摘要： A new reference occultation processing system (rOPS) will include a Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval chain with integrated uncertainty propagation. In this paper, we focus on wave-optics bending angle (BA) retrieval in the lower troposphere and introduce (1) an empirically estimated boundary layer bias (BLB) model then employed to reduce the systematic uncertainty of excess phases and bending angles in about the lowest 2 km of the troposphere and (2) the estimation of (residual) systematic uncertainties and their propagation together with random uncertainties from excess phase to bending angle profiles. Our BLB model describes the estimated bias of the excess phase transferred from the estimated bias of the bending angle, for which the model is built, informed by analyzing refractivity fluctuation statistics shown to induce such biases. The model is derived from regression analysis using a large ensemble of Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) RO observations and concurrent European Centre for Medium-Range Weather Forecasts (ECMWF) analysis fields. It is formulated in terms of predictors and adaptive functions (powers and cross products of predictors), where we use six main predictors derived from observations: impact altitude, latitude, bending angle and its standard deviation, canonical transform (CT) amplitude, and its fluctuation index. Based on an ensemble of test days, independent of the days of data used for the regression analysis to establish the BLB model, we find the model very effective for bias reduction and capable of reducing bending angle and corresponding refractivity biases by about a factor of 5. The estimated residual systematic uncertainty, after the BLB profile subtraction, is lower bounded by the uncertainty from the (indirect) use of ECMWF analysis fields but is significantly lower than the systematic uncertainty without BLB correction. The systematic and random uncertainties are propagated from excess phase to bending angle profiles, using a perturbation approach and the wave-optical method recently introduced by Gorbunov and Kirchengast (2015), starting with estimated excess phase uncertainties. The results are encouraging and this uncertainty propagation approach combined with BLB correction enables a robust reduction and quantification of the uncertainties of excess phases and bending angles in the lower troposphere.
关键词： wave-optics uncertainty propagation,bending angle retrievals,refractivity fluctuation statistics,GNSS radio occultation,boundary layer bias model
更新于2025-09-10 09:29:36
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Efficient bias reduction approach of time-of-flight-based wireless localisation networks in NLOS states
摘要： An efficient bias mitigation algorithm based on time of flight is proposed for positioning the target location and reducing the non-line-of-sight (NLOS) error and clock jitter error in three-dimensional wireless cooperative localisation networks. Through linearising the range-based expressions and utilising novel three-step weighted linear least squares algorithm, an algebraic solution of target can be derived, in which the clock jitter error and NLOS error can be alleviated effectively. Meanwhile, the Cramer–Rao lower bound (CRLB) is derived for the standard of performance evaluation. The location accuracy of the proposed algorithm is analysed and compared with the conventional methods through simulation experiment. The simulation results indicate that the precision of the proposed algorithm can approach the CRLB, what is more, the proposed algorithm can provide obvious improvements in positioning accuracy compared to the state-of-the-art approaches.
关键词： NLOS states,time of flight,three-dimensional,bias mitigation,wireless localisation,weighted linear least squares,Cramer–Rao lower bound
更新于2025-09-09 09:28:46
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Design of Bias-Free Operational Uni-traveling-Carrier Photodiodes by Transient Simulation for High-power Pulsed Millimeter-Wave Signal Generation in the Sub-THz Regime
摘要： In this paper, bias-free operational uni-traveling-carrier photodiodes (UTC-PDs) for high-power pulsed millimeter-wave signal generation in the sub-terahertz regime are designed and investigated. The reliability of the physics-based transient simulation is first demonstrated by comparing with reported experimental results. Then, the epitaxial layers are analyzed and optimized through transient simulation for bias-free operation and high-power pulsed millimeter-wave signal generation. The performance between original and optimal structure is compared under excitation of pulse train and sinusoidal optical signals. The results show that the peak output power of the modified UTC-PD under 100-GHz, 200-GHz, and 312.5-GHz pulse train excitation is 4.685 dBm, 1.128 dBm, and ? 4.653 dBm, improved by 2.05 dB, 5.15 dB, and 9.36 dB, respectively.
关键词： Bias-free,Optical communication,Millimeter-wave,Transient simulation,Terahertz communications,Sub-terahertz,Uni-traveling-carrier photodiodes (UTC-PD)
更新于2025-09-09 09:28:46
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A method to discern voltage dependent internal photoemission component from photoconductivity content in spectral response of metal-organic semiconductor-metal devices and evaluate the interface barriers
摘要： The ability to detect and determine a typically weak internal photoemission (IPE) signal from a usually strong photoconductivity (PC) signal within a spectral response (SR) measurement can be helpful in studying the interface properties of metal-semiconductor junctions, which are often critical for proper design and analysis of semiconductor electronic devices including organic photovoltaic devices. In this report, we propose a method to discern the voltage dependent IPE component from PC content in a measured SR of organic devices. The method is based on the ratio of SR measured at different voltage bias conditions in metal-organic semiconductor-metal devices. The separated IPE component, hence, can be used to estimate the associated interface barrier(s). The differentiation between IPE and PC is probably caused due to the barrier changing at the metal and organic semiconductor interface on the application of bias which causes a modulation in IPE signal with the applied bias. In this work, a theoretical basis for the method of characterisation has been developed. Based on the analysis, as an example, the barriers between [6, 6] phenyl C61 butyric acid methyl ester (PCBM) and electrodes indium tin oxide and aluminium for different bias voltages have been evaluated. This simple and elegant method of studying metal and organic semiconductor barrier, when applicable, can be helpful in device design and characterisation.
关键词： Spectral Response,Metal-Semiconductor Barrier,Bias Dependent Spectral Response,Internal Photoemission
更新于2025-09-09 09:28:46
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Smart controller for grid stabilization in the optoelectric system
摘要： The power generated from the optoelectric source in the conversion system and the connected system should satisfy several factors such as high efficiency, less total harmonic distortion, reduced cost, less complexity, better boosting capability, etc. The boosting capability can be achieved by means of single juncture or two juncture architecture in DC–DC boost converter. Among different architecture, the Z-source riven bias inverter controls the parameter on the AC and DC sections. The steady state quantity and the time-varying parameter are regulated by controlling the intonation index. The modulation indexes are framed by digital to look at its supervision theme in grid coupled structure that has certainly not been studied so far. Hence, in this paper, the Z-source riven bias electrical converter modeling has been studied in conjunction with the decoupled space vector modulation as a control technique. The deliberate theme is studied and simulated by using a MATLAB/Simulink model to approve the analysis and simulations.
关键词： digital space vector modulation,Z-source inverter,riven bias inverter,complete harmonic distortion,Optoelectric source
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 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Singapore (2018.7.16-2018.7.19)] 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA) - Characterization of Bandgap Engineering on Operative Transistor Devices by Spectral Photon Emission
摘要： In modern IC technologies, it is very common to use germanium enriched silicon in order to increase field effect transistor (FET) channel carrier mobility for high performance. The germanium content modifies the effective semiconductor band gap EG. Thus, the bandgap energy EG is an important technology performance parameter. EG can be obtained in an LED-like operation of electronic devices, requiring forward biased p-n junctions. P-n junctions in FETs are source or drain to body diodes, usually grounded or reversely biased. This investigation applies a bias to the body that can trigger parasitic forward operation of the source/drain to body p-n junction in any FET. Spectral photon emission (SPE) is taken here as non-destructive in operative method to characterize engineered bandgaps transistor devices, while the device remains fully functional. Proving this technique with the nominal silicon bandgap on an (unstrained) 120nm technology FET, the characterization capability for bandgap engineering is successfully demonstrated using SiGe:C HBT. In IC technology, Ge enriched silicon is recently often used to increase channel carrier mobility. As a next step, 14/16nm p-type FinFET devices have been investigated by applying a bias voltage to the body and thereby activating one of the body/diffusion p-n junctions in forward bias. By measuring the spectral distribution of emission intensity through the backside of the operating device with an InGaAs detector, EG of the engineered bandgap can be determined in the FinFETs as well, in case of the investigated p-type FinFETs to 0.84 eV. This opens a new path for contactless fault isolation by quantitative local determination of bandgap engineering.
关键词： Bandgap engineering,body diode,heterojunction bipolar transistor,body bias voltage,contactless fault isolation,parasitic operation,FinFET,germanium,MOSFET,p-n junction,bandgap characterization,spectral photon emission,SiGe,HBT
更新于2025-09-04 15:30:14
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The Effect of Microwave Annealing of Reliability Characteristics on Amorphous IGZO Thin Film Transistors
摘要： Amorphous oxide semiconductors (AOSs) are attracted much attention due to high mobility, low temperature deposition, ?exible, transmission, and uniformity. The thin ?lm transistors (TFTs) with a-IGZO thin ?lm as active layer perform higher ?eld-effect mobility (>10 cm2/V · S), larger I on/I off ratio (>106), smaller subthreshold swing and better stability against electrical stress. LaAlO3/ZrO2 is employed as gate electrode and gate dielectric layer for a-IGZO TFTs, under the premise that performance of a-IGZO TFTs without decreasing. Due to the good selectivity of energy transformation and rapid heating rate, microwave annealing is applied to improve the device reliability in the investigation. With adjusting the parameter of microwave annealing, the effect on reliability characteristics of a-IGZO TFTs is studied.
关键词： Microwave Annealing,Stretched-Exponential Model,IGZO TFTs,Positive Bias Stress
更新于2025-09-04 15:30:14
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Anomalous Positive Bias Stress Instability in MoS2 Transistors with High-hydrogen-concentration SiO2 gate dielectrics
摘要： For the first time, the anomalous positive bias stress instability of the back gated monolayer polycrystal molybdenum disulfide with field-effect high-hydrogen-concentration SiO2 gate dielectrics is reported in this letter. It is found the threshold voltage shifts exhibits a pronounced turnaround behavior from a positive shift to a negative shift when enlarging the stress voltage and stress time. We relate this anomalous positive bias instability to two physical processes, charge trapping and hydrogen release and migration.
关键词： MoS2 Transistor,Anomalous Positive Bias Stress Instability
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) - Avalanche rugged 1200 V 80 m Ω SiC MOSFETs with state-of-the-art threshold voltage stability
摘要： 1200 V 80 m? SiC MOSFETs were developed for 150 mm wafer mass production. Avalanche ruggedness was confirmed by measuring the failure distribution in unclamped inductive switching (UIS) for five wafers. The high voltage blocking reliability was verified by running 1000hr high temperature reverse bias tests for totally 770 devices without failures. The process conditions were optimized for gate oxide integrity and to minimize threshold voltage (VTH) drift both during positive and negative bias stress. Significant reductions of extrinsic defects in the gate oxide breakdown distributions were obtaine d using optimize d process conditions for both product die s and NMO S capacitors. State -of-the -art VTH stability was ve rified by transient measurements of VTH drift during gate bias stress for packaged 80 m? SiC MOSFETs.
关键词： gate oxide integrity,avalanche ruggedness,SiC MOSFET,bias temperature instability
更新于2025-09-04 15:30:14