We present a new lateral Schottky-based rectifier called the charge-plasma diode realized on ultrathin silicon-on-insulator. The device utilizes the workfunction difference between two metal ...contacts, palladium and erbium, and the silicon body. We demonstrate that the proposed device provides a low and constant reverse leakage-current density of about 1 fA/μm with ON/OFF current ratios of around 10 7 at 1-V forward bias and room temperature. In the forward mode, a current swing of 88 mV/dec is obtained, which is reduced to 68 mV/dec by back-gate biasing.
In this article, the avalanche capability of the 1.2-kV 4H-SiC junction barrier Schottky (JBS) and merged p-i-n Schottky (MPS) diodes is investigated through simulation and experiments. For MPS ...diodes, the width of the wide P+ region (<inline-formula> <tex-math notation="LaTeX">{W} </tex-math></inline-formula>) is found to have great effects on the device avalanche capability. MPS diodes with varied <inline-formula> <tex-math notation="LaTeX">{W} </tex-math></inline-formula>-values (3-20 <inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula>) and JBS diode are designed and fabricated, and their avalanche energy/current capability is tested with unclamped inductive switching tests. The experimental results show that the MPS diode has an optimized avalanche capability at <inline-formula> <tex-math notation="LaTeX">{W} =8 </tex-math></inline-formula>-<inline-formula> <tex-math notation="LaTeX">\mu \text{m} </tex-math></inline-formula> design. Simulation study reveals that the avalanche current is mainly distributed at the edges of the P+ regions in the JBS/MPS diodes as a result of the curvature-effect-induced electric field crowding. The localized current crowding and unbalanced current distribution in the avalanche mode contribute to a reduced effective power dissipation area and a weaker avalanche capability. The current nonuniformity coefficient (<inline-formula> <tex-math notation="LaTeX">{k} </tex-math></inline-formula>) is used to characterize the severity of the current unbalance, and it is found that <inline-formula> <tex-math notation="LaTeX">{k} </tex-math></inline-formula> declines as <inline-formula> <tex-math notation="LaTeX">{W} </tex-math></inline-formula> increases when <inline-formula> <tex-math notation="LaTeX">{W} = {3}-8~\mu \text{m} </tex-math></inline-formula> and then gets increased when <inline-formula> <tex-math notation="LaTeX">{W} </tex-math></inline-formula> exceeds <inline-formula> <tex-math notation="LaTeX">{8}~\mu \text{m} </tex-math></inline-formula>. Both the experimental and simulation results indicate that the MPS diode is superior to the JBS diode in avalanche capability, and the width of the wide P+ region in the MPS diode has an optimal design (<inline-formula> <tex-math notation="LaTeX">8~\mu \text{m} </tex-math></inline-formula> in this article) which corresponds to the alleviated current crowding issue and 9%-19% improvement of the avalanche capability.
•More detailed models are proposed to emulate the multi-crystalline solar cell/module.•Moth-Flame Optimizer (MFO) is proposed for the parameter extraction process.•The performance of MFO technique is ...compared with the recent optimization algorithms.•MFO algorithm converges to the optimal solution more rapidly and more accurately.•MFO algorithm accomplished with three diode model achieves the most accurate model.
As a result of the wide prevalence of using the multi-crystalline silicon solar cells, an accurate mathematical model for these cells has become an important issue. Therefore, a three diode model is proposed as a more precise model to meet the relatively complicated physical behavior of the multi-crystalline silicon solar cells. The performance of this model is compared to the performance of both the double diode and the modified double diode models of the same cell/module. Therefore, there is a persistent need to keep searching for a more accurate optimization algorithm to estimate the more complicated models’ parameters. Hence, a proper optimization algorithm which is called Moth-Flame Optimizer (MFO), is proposed as a new optimization algorithm for the parameter extraction process of the three tested models based on data measured at laboratory and other data reported at previous literature. To verify the performance of the suggested technique, its results are compared with the results of the most recent and powerful techniques in the literature such as Hybrid Evolutionary (DEIM) and Flower Pollination (FPA) algorithms. Furthermore, evaluation analysis is performed for the three algorithms of the selected models at different environmental conditions. The results show that, MFO algorithm achieves the least Root Mean Square Error (RMSE), Mean Bias Error (MBE), Absolute Error at the Maximum Power Point (AEMPP) and best Coefficient of Determination. In addition, MFO is reaching to the optimal solution with the shortest execution time when it is compared with the other tested algorithms.
Metal halide perovskites have drawn significant interest in the past decade. Superior optoelectronic properties, such as a narrow bandwidth, precise and facile tunable luminance over the entire ...visible spectrum, and high photoluminescence quantum yield of up to ≈100%, render metal halide perovskites suitable for next‐generation high‐definition displays and healthy lighting systems. The external quantum efficiency of perovskite light‐emitting diodes (LEDs) increases from 0.1 to 11.7% in three years; however, the energy conversion efficiency and the long‐term stability of perovskite LEDs are inadequate for practical application. Strategies to optimize the emitting layer and the device structure, with respect to material design, synthesis, surface passivation, and device optimization, are reviewed and highlighted. The long‐term stability of perovskite LEDs is evaluated as well. Meanwhile, several challenges and prospects for future development of perovskite materials and LEDs are identified.
Fascinating metal halide perovskite nanomaterials are revolutionary to the field of displays and lighting. Strategies toward high performance perovskite light‐emitting diodes (LEDs) concerning the optimization of emitting materials and device structures are reviewed. The long‐term stability of perovskite LEDs are discussed as well. Challenges and prospects that are crucial for the development of perovskite materials and LEDs are identified.
Blue organic luminescent materials play a crucial role in full‐color display and white lighting but efficient ones meeting commercial demands are very rare. Herein, the design and synthesis of ...tailor‐made bipolar blue luminogens with an anthracene core and various functional groups are reported. The thermal stabilities, photophysical properties, electronic structures, electrochemical behaviors, carrier transport abilities, and electroluminescence performances are systematically investigated. The luminogen TPE‐TAPBI containing a tetraphenylethene moiety shows aggregation‐induced emission, while another luminogen TriPE‐TAPBI bearing a triphenylethene unit exhibits light aggregation‐caused quenching. In comparison with TriPE‐TAPBI, TPE‐TAPBI has stronger blue emission in neat film and functions more efficiently in nondoped organic light‐emitting diodes (OLEDs). High maxima current, power, and external quantum efficiencies of 7.21 cd A−1, 6.78 lm W−1, and 5.73%, respectively, are attained by the nondoped blue OLED of TPE‐TAPBI (CIEx,y = 0.15, 0.16). Moreover, efficient two‐color hybrid warm white OLEDs (CIEx,y = 0.457, 0.470) are achieved using TPE‐TAPBI neat film as the blue‐emitting component, which provide total current, power, external quantum efficiencies of up to 70.5 lm W−1, 76.0 cd A−1, and 28% at 1000 cd m−2, respectively. These blue and white OLEDs are among the most efficient devices with similar colors in the literature.
A thermally stable blue fluorescent material with aggregation‐induced emission and bipolar carrier transport properties is developed, based on which highly efficient blue organic light‐emitting diodes (OLEDs) and hybrid white OLEDs are attained.
Solution‐processed organic light‐emitting diodes (OLEDs) with thermally activated delayed fluorescent (TADF) material as emitter have attracted much attention because of their low cost and high ...performance. However, exciton quench at the interface between the hole injection layer, poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), and emitting layer (EML) in devices can lead to low device performance. Here, a novel high triplet energy (2.89 eV) and crosslinkable hole‐transporting material grafted with oxetane groups, N,N‐bis(4‐(6‐((3‐ethyloxetan‐3‐yl)methoxy)hexyloxy)phenyl)‐3,5‐di(9H‐carbazol‐9‐yl)benzenamine (Oxe‐DCDPA)), as crosslinked hole transport layer (HTL) into the interface of PEDOT:PSS layer and EML is proposed for prevention of exciton quenching, and among the reported devices with single HTL in solution‐processed TADF‐OLED, the highest external quantum efficiency (EQE)/luminous efficiency (ηL) of 26.1%/94.8 cd A−1 and 24.0%/74.0 cd A−1 are achieved for green emission (DACT‐II as emitter) and bluish‐green emission (DMAC‐TRZ as emitter), respectively. Further improvement, using double HTLs, composed of N,N′‐bis(4‐(6‐((3‐ethyloxetan‐3‐yl)methoxy))‐hexylphenyl)‐N,N′‐diphenyl‐4,4′‐diamine with high hole mobility and Oxe‐DCDPA with high triplet energy, leads to the highest EQE/ηL of 30.8%/111.9 cd A−1 and 27.2%/83.8 cd A−1 for green emission and bluish‐green emission, respectively. These two devices show the high maximum brightness of 81 100 and 70 000 cd m−2, respectively.
Double hole transport layers provide an effective prevention of exciton quench by poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) and facilitate hole injection/transporting to a thermally activated delayed fluorescent (TADF) emitting layer, resulting in solution‐processed bluish‐green and green emission TADF device with high maximum brightness and luminous efficiency/external quantum efficiency of 70 000 cd m−2, 83.8 cd A−1/27.2% and 81 100 cd m−2, 111.9 cd A−1/30.8%, respectively.
Critical design parameters for AlGaN/GaN Schottky barrier diodes (SBDs) are analyzed in this work using TCAD computations and detailed experiments. A comprehensive TCAD-based computational modeling ...approach is developed for GaN-based SBD. Breakdown mechanisms in SBD for unintentionally doped (UID) buffer, Fe-doped buffer and C-doped buffer are studied. For the first time, we have reported impact of anode recess, on breakdown and leakage behavior of SBD, in correlation with interface defects. Using these insights an optimum recess design strategy has been presented and is validated experimentally. Furthermore, for the first time, we have revealed critical repercussions of the field plate termination on SBD's breakdown, leakage as well as transient behavior. Forward and reverse recovery measurements were carried out to study the diode's transient performance as a function of field plate design. Various performance matrices such as diode current collapse, reverse current overshoot and reverse recovery time were studied experimentally as a function of field plate design. Moreover, the field plate-dependent electro-thermal behavior of SBD was studied using TCAD computations and experiments. Using the systematic device design approach we have experimentally demonstrated large periphery SBD with 15 A forward current at 5.5 V.
We report on vertical GaN junction barrier Schottky (JBS) diodes formed by Mg ion implantation and ultrahigh -pressure annealing (UHPA). The static ON-state characteristics of the diodes show an ...ideality factor of 1.05, a turn-on voltage of ~0.7 V, a current rectification ratio of <inline-formula> <tex-math notation="LaTeX">\sim 10^{11} </tex-math></inline-formula>, and a low differential specific ON-resistance that scales with Schottky stripe width in fair agreement with the analytical model. The reverse leakage dependence on Schottky stripe width also agrees well with the analytical model. Implanted p-n junction diodes fabricated on the same wafer exhibit avalanche breakdown in reverse bias with a positive temperature coefficient, but the forward current is limited by a series barrier. Temperature-dependent current-voltage measurements of th p-n diodes verify the presence of the implanted p-n junction and reveal an additional 0.43-eV barrier, which we hypothesize arises from a p-Schottky contact and forms a second diode back-to-back with the p-n junction. This interpretation is supported by analysis of the capacitance-voltage characteristics of the implanted p-n diodes, epitaxial p-n diodes fabricated with intentional p-Schottky contacts, and comparison to TCAD simulations. Ultimately, the presence of the p-Schottky contact does not hinder JBS diode operation. The use of diffusion-aware designs and/or diffusion reduction represents future directions for Mg implantation technology in GaN power devices.
Commercial photovoltaic (PV) modules are made of different PV cell technologies such as monocrystalline, multicrystalline, amorphous silicon, and copper indium diselenide. Usually, a singleor a ...double-diode PV model is used to model the output characteristic. However, it is unclear which PV model is optimal for each PV cell technology as the modeling accuracy is dependent on the PV model used. To fill up this research gap, a generalized multidimension (n × m) diode PV model is proposed in this paper to determine the optimal PV model. The proposed PV model allows the diode network to be configured to better fit the output characteristics of different PV cell technologies. Both simulation and experimental results are presented to illustrate the advantages of the proposed model. From the results, the optimal PV model that matches each of the cell technology is established. They can be used as a reference PV model for future works.
This article presents a fully integrated terahertz (THz) comb/pulse radiator and a broadband frequency-comb heterodyne receiver for sensing and imaging applications. The chipset is fabricated in the ...GlobalFoundries 90-nm SiGe BiCMOS process. The comb radiator utilizes p-i-n diode sharp reverse recovery to generate THz frequency comb/pulses. The repetition rate of the radiated pulses is locked to a stable off-chip source, which can be adjusted to as high as 15 GHz. By using a low-phase noise off-chip source rather than an on-chip oscillator, low phase noise and high-frequency stability are achieved. The phase noise of 405-GHz tone is −82 dBc at a 10-kHz offset frequency. The radiated tones are characterized from 220 GHz up to 1.1 THz using VDI SAX modules with the measured EIRP of −11, −15, and −36 dBm at 405, 500, and 750 GHz, respectively. In addition, a THz frequency comb detector using a Schottky barrier diode passive mixer is presented. The detector uses a broadband comb as LO for heterodyne detection of any arbitrary spectrum in mm-wave/THz band by adjusting the spacing of the LO comb from 100 s of MHz up to 15 GHz with a resolution of 2 Hz. The receiver chip is characterized from 220 up to 500 GHz with the measured NF of 24.5, 36, and 44 dB at 270, 405, and 495 GHz, respectively. Moreover, a dual-comb technique using the radiator and receiver chips is demonstrated, promising a compact low-cost solution for dual-comb sensing applications. The radiator and receiver chips consume a dc power of 40 and 38 mW, respectively.
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