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High-performance flat-type InGaN-based light-emitting diodes with local breakdown conductive channel
摘要： Flat-type InGaN-based light-emitting diodes (LEDs) without an n-type contact electrode were developed by using a local breakdown conductive channel (LBCC), and the effect of the In content of the InGaN quantum wells (QWs) on the local breakdown phenomenon was investigated. Electroluminescence and X-ray analyses demonstrated that the homogeneity and crystallinity of the InGaN QWs deteriorated as the In content of the InGaN QWs increased, thereby increasing the reverse leakage current and decreasing the breakdown voltage. After reverse breakdown with a reverse current of several mA, an LBCC was formed on the GaN-based LEDs. The surface size and anisotropic shape of the LBCC increased as the indium content of the InGaN QWs in the LEDs increased. Moreover, a flat-type InGaN LED without an n-type electrode was developed by using the LBCC. Notably, the resistance of the LBCC decreased with increasing indium content in the InGaN QWs, leading to lower resistance and higher light emission of the flat-type InGaN-based LEDs without an n-type contact electrode.
关键词： light-emitting diodes,reverse leakage current,quantum wells,breakdown voltage,InGaN,local breakdown conductive channel
更新于2025-09-12 10:27:22
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Enhancement in photovoltaic properties of bismuth ferrite/zinc oxide heterostructure solar cell device with graphene/indium tin oxide hybrid electrodes
摘要： Integrating of ferroelectric thin films with two-dimensional materials may provide a novel and unique characteristics in the field of optoelectronics due to the coupling of their distinctive intrinsic features. A heterostructure (bismuth ferrite/zinc oxide) device is fabricated with different types of the electrode to enhance the power conversion efficiency (PCE). A single-phase multiferroic BFO thin film is grown by atomic layer deposition (ALD) method and annealed in different environments such as helium, nitrogen, and oxygen. We investigated the effect of annealing parameters and different types of electrodes on solar cell applications. We observed that the leakage current 10 orders of magnitude was reduced by decreasing in the dielectric loss. Further, the power conversion efficiency (PCE) is improved from 4.1% to 7.4% with a hybrid transparent electrode (graphene/indium tin oxide). The value of PCE is further increased at a low temperature. So, the improvement in the key parameter of bismuth ferrite thin-film evidently highlights the importance of annealing atmosphere and graphene as an electrode in BFO thin film applications in optoelectronics.
关键词： Power conversion efficiency,Transparent electrode,Annealing atmosphere,Atomic layer deposition,Graphene,Leakage current
更新于2025-09-12 10:27:22
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[IEEE 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Baltimore, MD, USA (2019.9.29-2019.10.3)] 2019 IEEE Energy Conversion Congress and Exposition (ECCE) - Leakage Current Mitigation in Current-Source Inverter based Transformerless Photovoltaic System using Active Zero-State Space Vector Modulation
摘要： Suitable space vector modulation (SVM) schemes for current-source inverters (CSIs) with leakage current mitigation capability has not been well explored yet. In this study, a novel SVM scheme is proposed, with which the leakage current in a CSI-based transformerless photovoltaic system can be significantly suppressed. Finally, some simulations are carried out on a three-phase current-source converter (CSC), the results verify the effectiveness of the proposed SVM scheme.
关键词： Three-phase current-source inverter,space vector modulation,leakage current
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - A New Single-Phase Single-Stage Photovoltaic Grid-Tied Inverter with Leakage Current Eliminating and Power Decoupling
摘要： Common-mode leakage current and double-line-frequency power oscillation are two major challenges of non-isolated single-phase grid-tied inverters. To overcome these two challenges, this paper proposes a new single-phase single-stage inverter for photovoltaic grid-tied systems, which consist of two switches, three capacitors, two inductors, and one diode. The proposed topology allows the negative pole of the photovoltaic panel to be directly connected to the neutral line of the utility grid so that the common-mode leakage current is eliminated completely. Then a mixed modulation strategy combining pulse width modulation and pulse frequency modulation is proposed to suppress the double-line-frequency power oscillation. Two of the capacitors are utilized to handle the power difference between the AC and DC sides, and the other is utilized to implement zero voltage switching. The proposed inverter is also capable of outputting reactive power. The validity of the proposed inverter is veri?ed by simulation.
关键词： zero voltage switching,double-line-frequency power oscillation,grid-tied inverter,common-mode leakage current,mixed modulation strategy
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - Xi'an, China (2019.6.3-2019.6.6)] 2019 IEEE 10th International Symposium on Power Electronics for Distributed Generation Systems (PEDG) - An Extraction Method for the Parasitic Capacitance of the Photovoltaic Module Based on the Oscillation of the Leakage Current
摘要： In photovoltaic (PV) plant, the parasitic capacitance between the PV module and the ground causes leakage current in the non-isolated systems. The case can be deteriorated in the rain environment, because increases dramatically due to the rain water. This paper presents an extraction method for the parasitic capacitance between the PV module and the ground. Unlike the common analytical, numerical way and direct measurement method, the parasitic capacitance is obtained through measurement of the leakage current oscillation. A full-bridge inverter is used to explain the principle as well as for the measurement. Theoretical calculation, MATLAB simulations and experimental measurements finally verify the accuracy of the proposed methods. The experimental results are shown to validate the method works well.
关键词： photovoltaic module,parasitic capacitance,leakage current,oscillation
更新于2025-09-11 14:15:04
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A New Transformer-less Five-level Grid-Tied Inverter for Photovoltaic Applications
摘要： A new fundamental structure of a single-phase transformer-less grid connected multilevel inverter based on a switched-capacitor structure is presented in this study. By employing the series-parallel switching conversion of the integrated switched-capacitor module in a packed unit, attractive features for the proposed inverter can be obtained such as high efficiency and boosting ability within a single stage operation. Also, using a common grounding technique provides an additional advantage of reducing the leakage current. Moreover, the presented structure generates a multilevel waveform at the output voltage terminals which reduces the harmonics in the system. A peak current controller is utilized for triggering the gate of the power switches and controlling both the active and reactive powers. This results in a tightly controlled current with an appropriate quality that can be injected to the grid using a single source resource. Operating procedures, design considerations, comparison studies and test results of a 620 W prototype are also presented to validate the accuracy and feasibility of the proposed multilevel inverter.
关键词： Grid connected multilevel inverter,transformer-less inverter,switched-capacitor based structure,leakage current elimination
更新于2025-09-11 14:15:04
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Elucidating the effect of shunt losses on the performance of mesoporous perovskite solar cells
摘要： Mesoporous perovskite solar cells (MPSCs) suffer from various types of charge carrier losses, where shunt losses usually dominate. Herein, we perform a systematic study to investigate the impact of such losses on the photovoltaic performance of methylammonium lead iodide (MAPbI3)-based MPSCs. The shunt losses in the MPSCs are attributed to the leakage current and the non-geminated recombination losses. We also demonstrate that these losses can be reduced by the incorporation of appropriate thickness of compact titanium oxide (c-TiO2) interlayer between FTO and mesoporous TiO2 (m-TiO2). As a result, MPSCs exhibit higher open-circuit voltage (VOC) of 1.05 V, short-circuit current density (JSC) of 23.27 mA cm?2, and the power conversion efficiency (PCE) of 17.69% under one-sun illumination conditions. The improved device performance was attributed to (i) the efficient blocking of holes, (ii) the decrease of leakage current, and (iii) the suppression of the non-geminated recombination losses in the cells. The effect of the c-TiO2 layer thickness on the series resistance (RS), shunt resistance (RSh), and the non-geminated recombination were also discussed in detail.
关键词： Non-geminated recombination losses,Series and shunt resistance,Electron transport layer,Leakage current,Perovskite solar cell
更新于2025-09-11 14:15:04
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Improved Reverse Leakage Current in GaInN-based LEDs with a Sputtered AlN Buffer Layer
摘要： In this study, the improvement of reverse leakage current characteristics with a sputtered (SP) -AlN buffer layer in GaInN-based green light-emitting diodes (LEDs) has been presented for the first time. To understand the origin of the improvement, a detailed review and careful analysis of reverse leakage current characteristics were performed. The review and analysis identified that the improvement was primarily caused by the suppression of variable-range-hopping process obtained by replacing conventional low-temperature GaN buffer. Verification that threading dislocations and V- defects can enhance the variable-range-hopping process has been received. We believe that this study will contribute to the realization of green LEDs with advantages of high reliability, a long lifetime, and electrical robustness.
关键词： reverse leakage current,dot-like local emission,light-emitting diodes,Frenkel-Poole emission,variable-range-hopping
更新于2025-09-11 14:15:04
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An Integrated Semi-Double Stage based Multilevel Inverter with Voltage Boosting Scheme for Photovoltaic Systems
摘要： This paper proposes a single-phase, seven-level, transformerless inverter, employing a semi-double stage based conversion technique, which is particularly suitable for PV applications. The proposed configuration achieves voltage boosting using a non-isolated interleaved buck-boost converter, which is fused with the inverter configuration through two switched capacitors (SC). The interleaved front-end boost stage is capable of achieving a voltage gain of three while resulting in reduced peak current stress on the switching devices. In this topology, a part of the load power is transferred directly from the PV source, while the other part is transferred through the SCs. The proposed topology and the associated PWM technique are capable of reducing the leakage current by isolating the terminals of the PV source during the freewheeling state. This paper also presents a thorough analysis of the stray capacitor voltage and the common-mode voltage (CMV). These analyses reveal that the high-switching frequency transitions are eliminated in both of these waveforms. Furthermore, the proposed topology results in the reduction of the low-frequency transitions in the stray capacitor voltage and the CMV, which results in further reduction of the leakage current. The simulation and experimental results are in agreement with the mathematical analysis of the proposed inverter.
关键词： Leakage current minimization,Pulse width modulation inverters,Multilevel-inverter,Voltage boosting,Semi-double stage system,Photovoltaic systems
更新于2025-09-11 14:15:04
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Effect of Proton Radiation on Ultra-Wide Bandgap AlN Schottky Barrier Diodes
摘要： Lateral Pd/n-AlN Schottky barrier diodes (SBDs) were fabricated and subjected to 3 MeV proton irradiation at various fluences. Electrical and material characterization analysis was performed before and after each radiation fluence to quantify the change in device characteristics. It was found that the SBDs performed reliably up to a proton irradiation fluence of 5×1013 cm-2, with little or no change in the key device performance such as current, turn-on voltage, ideality factor, and breakdown voltage, etc. The electrical characteristics of the SBDs was well predicted using a standard thermionic emission theory. The performance of the SBDs showed a significant degradation after a high-fluence irritation of 5×1015 cm-2, where the current of the SBDs dropped two orders of magnitude. Material and surface characterizations, including atomic force microscopy and X-ray diffraction, indicated a consistent degradation in the AlN bulk crystal quality and a drastic increase in surface roughness. These results provide valuable information on the radiation properties of AlN electronics and can serve as important references for the future development of high performance AlN devices for extreme environment applications.
关键词： surface roughness,leakage current,radiation effects,Aluminum nitride,breakdown voltage,barrier height,Schottky barrier diodes,ideality factor,turn on voltage
更新于2025-09-11 14:15:04