scholarly journals Деградация ультрафиолетовых светодиодов с квантовыми ямами InGaN/GaN, вызванная кратковременными воздействиями током

2022 ◽  
Vol 92 (2) ◽  
pp. 283
Author(s):  
А.М. Иванов ◽  
А.В. Клочков
Keyword(s):  
Comparative Analysis ◽  
Quantum Wells ◽  
Quantum Efficiency ◽  
Exposure Time ◽  
External Quantum Efficiency ◽  
Forward Bias ◽  
Accelerated Aging ◽  
Short Term ◽  
Physical Mechanisms ◽  
Uv Leds

A comparative analysis of the initial stages of degradation of ultraviolet and blue LED structures with InGaN / GaN quantum wells is carried out. In the mode of accelerated aging, the structures were subjected to short-term, sequential exposure to currents of 80–190 mA at forward bias. The exposure time did not exceed three hours. There was an increase (up to 20%) in the external quantum efficiency. The most probable physical mechanisms explaining the changes in InGaN / GaN LEDs are presented and possible ways to slow down the aging of UV LEDs are outlined.

scholarly journals Study of characteristics of LEDs based on InGaN/GaN quantum wells under short electric impacts accompanied by joule heating

2021 ◽  
Vol 2103 (1) ◽  
pp. 012189
Author(s):  
A M Ivanov ◽  
A V Klochkov
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
Joule Heating ◽  
Uv Light ◽  
Forward Bias ◽  
Low Frequency ◽  
Accelerated Aging ◽  
Light Emitting ◽  
Physical Mechanisms ◽  
Frequency Current

Abstract Results are presented of a study of commercial blue and UV light-emitting diodes based on structures with InGaN/GaN quantum wells. An accelerated aging was provided by currents of 80 – 190 mA under a forward bias with duration not exceeding 3 h. The study demonstrated the possible rise in the external quantum efficiency by 20% relative to that in the starting samples. The possible physical mechanisms responsible for the rise in the quantum efficiency and for the formation of a low-frequency current noise are presented.

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

scholarly journals Record High External Quantum Efficiency of 19.2% Achieved in Light-Emitting Diodes of Colloidal Quantum Wells Enabled by Hot-Injection Shell Growth

2019 ◽  
Author(s):  
Baiquan Liu ◽  
Yemliha Altintas ◽  
Lin Wang ◽  
Sushant Shendre ◽  
Manoj Sharma ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
High Performance ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Shell Growth ◽  
Light Emitting ◽  
Hot Injection ◽  
Key Factor

<p> Colloidal quantum wells (CQWs) are regarded as a new, highly promising class of optoelectronic materials thanks to their unique excitonic characteristics of high extinction coefficient and ultranarrow emission bandwidth. Although the exploration of CQWs in light-emitting diodes (LEDs) is impressive, the performance of CQW-LEDs lags far behind compared with other types of LEDs (e.g., organic LEDs, colloidal quantum-dot LEDs, and perovskite LEDs). Herein, for the first time, the authors show high-efficiency CQW-LEDs reaching close to the theoretical limit. A key factor for this high performance is the exploitation of hot-injection shell (HIS) growth of CQWs, which enables a near-unity photoluminescence quantum yield (PLQY), reduces nonradiative channels, ensures smooth films and enhances the stability. Remarkably, the PLQY remains 95% in solution and 87% in film despite rigorous cleaning. Through systematically understanding their shape-, composition- and device- engineering, the CQW-LEDs using CdSe/Cd<sub>0.25</sub>Zn<sub>0.75</sub>S core/HIS CQWs exhibit a maximum external quantum efficiency of 19.2%. Additionally, a high luminance of 23,490 cd m<sup>-2</sup>, extremely saturated red color with the Commission Internationale de L’Eclairage coordinates of (0.715, 0.283) and stable emission are obtained. The findings indicate that HIS grown CQWs enable high-performance solution-processed LEDs, which may pave the path for CQW-based display and lighting technologies.</p>

Degradation of external quantum efficiency of AlGaN UV LEDs grown by hydride vapor phase epitaxy

2015 ◽  
Vol 12 (4-5) ◽  
pp. 349-352 ◽  
Author(s):  
Natalia Shmidt ◽  
Alexander Usikov ◽  
Eugenia Shabunina ◽  
Anton Chernyakov ◽  
Alexey Sakharov ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Vapor Phase ◽  
External Quantum Efficiency ◽  
Vapor Phase Epitaxy ◽  
Hydride Vapor Phase Epitaxy ◽  
Uv Leds

scholarly journals Nanoscale Characterization of V-defect in InGaN/GaN QWs LEDs using Near-Field Scanning Optical Microscopy

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 633 ◽  
Author(s):  
Li ◽  
Tang ◽  
Zhang ◽  
Guo ◽  
Li ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Optical Microscopy ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Near Field ◽  
Light Output ◽  
Current Injection ◽  
Light Output Power ◽  
Scanning Optical Microscopy ◽  
Near Field Scanning

The size of the V-defects in the GaN/InGaN-based quantum wells blue light-emitting diode (LED) was intentionally modified from 50 nm to 300 nm. High resolution photoluminescence and electroluminescence of a single large V-defect were investigated by near-field scanning optical microscopy. The current distribution along the {10-11} facets of the large defect was measured by conductive atomic force microscopy. Nearly 20 times the current injection and dominant emission from bottom quantum wells were found in the V-defect compared to its vicinity. Such enhanced current injection into the bottom part of quantum wells through V-defect results in higher light output power. Reduced external quantum efficiency droops were achieved due to more uniform carrier distribution. The un-encapsulated fabricated chip shows light output power of 172.5 mW and 201.7 mW at 400 mA, and external quantum efficiency drop of 22.3% and 15.4% for the sample without and with large V-defects, respectively. Modified V-defects provide a simple and effective approach to suppress the efficiency droop problem that occurs at high current injection, while improving overall quantum efficiency.

scholarly journals Низкочастотный шум в светодиодах на основе InGaN/GaN квантовых ям при электрических воздействиях, сопровождающихся возрастанием внешней квантовой эффективности

2021 ◽  
Vol 91 (1) ◽  
pp. 76
Author(s):  
А.М. Иванов
Keyword(s):  
Quantum Wells ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Physical Processes ◽  
Initial Value ◽  
A Current

The results of testing the degradation of LED structures with InGaN/GaN quantum wells are presented. An increase in the external quantum efficiency above the initial value was observed after passing a current of 150–170 mA. Possible physical processes leading to a change in quantum efficiency and an increase in low-frequency noise are considered.

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