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Suggestions on Efficiency Droop of GaN-based LEDs
摘要： InGaN/GaN-based light-emitting diodes (LEDs) are widely used in modern society and industry among different areas. However, InGaN/GaN LEDs suffer from an efficiency droop issue: The internal efficiency decreases during high current injection. The efficiency droop significantly affects the development of GaN-based LEDs devices in efficiency and light-output areas. Therefore, the improvement of the droop phenomenon has become a significant topic. This paper introduces several possible mechanisms of droop phenomenon based on different hypotheses including Auger Recombination, Carrier Delocalization and Electron Leakage. Furthermore, some proposals to mitigate efficiency droop, including semipolar LEDs, electron blocking layer(EBL), quaternary alloy and chip design will be discussed and analyzed. Also, it will provide some suggestions for the further optimization of droop phenomenon in each proposal.
关键词： electron blocking layer,semipolar LEDs,GaN-based LEDs,Auger Recombination,chip design,quaternary alloy,Carrier Delocalization,Electron Leakage,efficiency droop
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [AIP Publishing 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Bikaner, India (14a??15 October 2019)] 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019) - Effect of polarization field and Auger recombination on internal quantum efficiency of InGaN/GaN blue LED
摘要： InxGa1-x N/GaN blue LEDs faces significant efficiency droop issue. The causes of efficiency droop are Shockley Read Hall recombination (SRH), Auger recombination (AR), carrier delocalization and electron leakage. The SRH, Auger and electron leakage are functions of carrier concentration and temperature. InGaN/GaN superlattice has polarization electric field at interface. In this work we explore effect of polarization electric field on efficiency droop. It is shown that polarization field enhances Auger coefficient resulting in more droop in internal quantum efficiency of blue LED. Thus, for improvement in efficiency, polarization field required to be minimized which requires growth of the material in m- plane instead of c-plane.
关键词： efficiency droop,polarization electric field,Auger recombination,blue LED,InGaN/GaN
更新于2025-09-23 15:21:01
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AlInGaN-based superlattice p-region for improvement of performance of deep UV LEDs
摘要： A deep ultraviolet light-emitting diode (DUV LED) consisting of a specifically designed intermediate p-type region involving a superlattice quaternary nitride alloy has been proposed. The light output power of the proposed structure has been found significantly large; around 28.30 times high in comparison to the conventional structure, at the current density of 200 A/cm2. The maximum internal quantum efficiency of the proposed structure is 153.63% higher compared to the conventional one. Moreover, the efficiency droop has been reduced by 99.08%. Absence of abrupt potential barrier owing to the strain compensation provided by the superlattice p-AlInGaN layer offers an attractive solution for enhancing the hole injection into the active region leading to the improvement in performance of DUV LED.
关键词： Efficiency droop,Superlattice-AlInGaN,Strain compensation,DUV LED
更新于2025-09-23 15:21:01
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Thermal and efficiency droop in InGaN/GaN light-emitting diodes: decoupling multiphysics effects using temperature-dependent RF measurements
摘要： Multiphysics processes such as recombination dynamics in the active region, carrier injection and transport, and internal heating may contribute to thermal and efficiency droop in InGaN/GaN light-emitting diodes (LEDs). However, an unambiguous methodology and characterization technique to decouple these processes under electrical injection and determine their individual roles in droop phenomena is lacking. In this work, we investigate thermal and efficiency droop in electrically injected single-quantum-well InGaN/GaN LEDs by decoupling the inherent radiative efficiency, injection efficiency, carrier transport, and thermal effects using a comprehensive rate equation approach and a temperature-dependent pulsed-RF measurement technique. Determination of the inherent recombination rates in the quantum well confirms efficiency droop at high current densities is caused by a combination of strong non-radiative recombination (with temperature dependence consistent with indirect Auger) and saturation of the radiative rate. The overall reduction of efficiency at elevated temperatures (thermal droop) results from carriers shifting from the radiative process to the non-radiative processes. The rate equation approach and temperature-dependent pulsed-RF measurement technique unambiguously gives access to the true recombination dynamics in the QW and is a useful methodology to study efficiency issues in III-nitride LEDs.
关键词： InGaN/GaN light-emitting diodes,carrier dynamics,efficiency droop,pulsed-RF measurement,thermal droop
更新于2025-09-23 15:19:57
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Prominent Heat Dissipation in Perovskite Light-Emitting Diodes with Reduced Efficiency Droop for Silicon-Based Display
摘要： Solution-processed perovskite light-emitting diodes (LEDs) possess outstanding optoelectronic properties for potential solid-state display applications. However, poor device stability results in significant efficiency droop partly being ascribed to Joule heating when LEDs are operated at high current densities. Herein, we used monocrystal silicon (c-Si) as substrate and charge injection layer to alleviate the thermal affection in perovskite LED (PeLED). By incorporating silicon oxide (SiOx) and poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4’-(N-(4-butylphenyl) (TFB) layer to tune the charge injection balance in c-Si-based device, a PeLED achieves an external quantum efficiency of 2.12% with a current efficiency of 6.06 cd A-1. Benefiting from excellent heat dissipation of c-Si, the PeLEDs display reduced efficiency droop and extended operational lifetime. Furthermore, both electroluminescent (EL) dynamic information display and static pattern displays of c-Si-based PeLED have been successfully demonstrated. These results reveal the feasibility of potential practical c-Si-based PeLEDs with reduced efficiency droop for EL display applications.
关键词： efficiency droop,silicon substrate,perovskite light-emitting diode,display application,heat dissipation
更新于2025-09-23 15:19:57
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Nanoplatelet-Based Light-Emitting Diode and Its Use in All-Nanocrystal LiFi-like Communication
摘要： Since colloidal nanocrystals (NCs) were integrated as green and red sources for LCD displays, the next challenge for quantum dots has been their use in electrically driven light emitting diodes (LEDs). Among various colloidal nanocrystals, nanoplatelets (NPLs) appeared as promising candidates for light emitting devices because their two-dimensional shape allows a narrow luminescence spectrum, directional emission and high light extraction. To reach high quantum efficiency it is critical to grow core/shell structures. High temperature growth of the shells seems to be a better strategy than previously reported low temperature approaches to obtain bright NPLs. Here, we synthesize CdSe/CdZnS core/shell NPLs whose shell alloy content is tuned to optimize the hole injection in the LED structure. The obtained LED has exceptionally low turn-on voltage, long-term stability (>3100 h at 100 Cd.m-2), external quantum efficiency above 5% and luminance up to 35000 cd.m-2. We study the low-temperature performance of the LED and find that there is a delay of droop in terms of current density as temperature decreases. In the last part of the paper, we design a large LED (56 mm2 emitting area) and test its potential for LiFi-like communication. In such approach, the LED is not only a lightning source but also used to transmit a communication signal to a PbS quantum dot solar cell used as a broad band photodetector. Operating conditions compatible with both lighting and information transfer have been identified. This work paves the way toward an all nanocrystal-based communication setup.
关键词： efficiency droop,nanoplatelets,electronic transport,light emitting diode,nanocrystal-based communication
更新于2025-09-23 15:19:57
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Role of electron leakage on efficiency droop in AlxGa(1a??x)N/GaN ultraviolet LEDs
摘要： Highly efficient AlxGa1?xN/GaN deep ultraviolet LEDs are widely used for water purification and medical diagnostics. However, these LEDs undergo efficiency reduction problem known as efficiency droop. Many causes of efficiency droop have been found; out of these one strong cause is electron leakage (EL). Electrons are leaked from the active region of the device before recombination. Electron leakage in AlxGa1?xN/GaN deep ultraviolet LEDs depends on temperature and carrier concentration. Here we investigate efficiency droop phenomenon of AlxGa1?xN/GaN deep ultraviolet LEDs under the effect of polarization charges on carrier concentrations. It is found that efficiency is decreased when polarization and applied current increases.
关键词： Electron leakage (EL),Efficiency droop,Current density,UV LED,IQE,AlGaN/GaN
更新于2025-09-23 15:19:57
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Coaxial semipolar InGaN/GaN microwire array LED with substantially suppressed efficiency droop
摘要： GaN nano/micro-structure based light-emitting diodes (LEDs) have drawn much attention owing to their potential applications in display and optoelectronics integration. Here, we have fabricated coaxial semipolar InGaN/GaN multiple quantum wells (MQWs) microwire array LED with superior performances in suppressing efficiency droop. The results show that our as-synthesized microwire has two semipolar planes (1 01), and the InGaN/GaN MQWs have superior crystal quality. In addition, the efficiency droop ratio of our device is about 9.7% as the injected current increases from 3 to 100 A/cm2, which is largely declined by 47% compared with that of the conventional polar c-plane LEDs. Meanwhile, the microwire array LED reveals a small wavelength shift (3nm) as the injected current increases from 3 to 23 A/cm2. The effective advances in the device should be attributed to the weaker quantum-confined stark effect of InGaN/GaN MQWs in semipolar plane. This work proposes a high repeatability method to fabricate microwire array LED for future optoelectronic integrated systems.
关键词： LED,Quantum-confined stark effect,Semipolar,GaN microwire array,Efficiency droop
更新于2025-09-16 10:30:52
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Kinetic Monte Carlo simulations of the dynamics of a coupled system of free and localized carriers in AlGaN
摘要： A model for the dynamics of a coupled system of free and localized carriers in semiconductors with strong carrier localization is suggested. Kinetic Monte Carlo technique is exploited for simulations. The model is verified by fitting the simulated and experimental temperature dependences of photoluminescence (PL) band intensity, peak position, and band width, and the carrier density dependence of PL efficiency in AlGaN quantum wells. The influence of carrier localization conditions on the dominating carrier migration and recombination processes is revealed. The efficiency droop effect is shown to be caused by peculiarities of carrier localization without significant influence of Auger recombination.
关键词： AlGaN,nitrides,carrier localization,efficiency droop,Monte Carlo simulations
更新于2025-09-12 10:27:22