Impact of Radiative and Nonradiative Recombination Processes on the Efficiency-Droop Phenomenon in InxGa1−xN Single Quantum Wells Studied by Scanning Near-Field Optical Microscopy

2016 ◽  
Vol 6 (4) ◽  
Author(s):  
Yoichi Kawakami ◽  
Akio Kaneta ◽  
Akira Hashiya ◽  
Mitsuru Funato
Keyword(s):  
Quantum Wells ◽  
Optical Microscopy ◽  
Near Field ◽  
Efficiency Droop ◽  
Nonradiative Recombination ◽  
Single Quantum ◽  
Recombination Processes

scholarly journals Nanoscale Characterization of Surface Plasmon-Coupled Photoluminescence Enhancement in Pseudo Micro Blue LEDs Using Near-Field Scanning Optical Microscopy

Nanomaterials ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 751
Author(s):  
Yufeng Li ◽  
Aixing Li ◽  
Ye Zhang ◽  
Peng Hu ◽  
Wei Du ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Optical Microscopy ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Near Field ◽  
Excitation Power ◽  
Localized Surface Plasmon ◽  
Excitation Density ◽  
Multiple Quantum ◽  
Excitation Power Density

The microcave array with extreme large aspect ratio was fabricated on the p-GaN capping layer followed by Ag nanoparticles preparation. The coupling distance between the dual-wavelength InGaN/GaN multiple quantum wells and the localized surface plasmon resonance was carefully characterized in nanometer scale by scanning near-field optical microscopy. The effects of coupling distance and excitation power on the enhancement of photoluminescence were investigated. The penetration depth was measured in the range of 39–55 nm depending on the excitation density. At low excitation power density, the maximum enhancement of 103 was achieved at the optimum coupling distance of 25 nm. Time-resolved photoluminescence shows that the recombination life time was shortened from 5.86 to 1.47 ns by the introduction of Ag nanoparticle plasmon resonance.

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.

Carrier leakage effect on efficiency droop in InGaN/GaN light-emitting diodes

2016 ◽  
Vol 30 (20) ◽  
pp. 1650221 ◽  
Author(s):  
Yang Huang ◽  
Zhiqiang Liu ◽  
Xiaoyan Yi ◽  
Yao Guo ◽  
Shaoteng Wu ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Light Emitting Diodes ◽  
Efficiency Droop ◽  
Nonradiative Recombination ◽  
Leakage Currents ◽  
Light Emitting ◽  
New Model ◽  
Leakage Effect ◽  
Text Model ◽  
The Common

A new model for efficiency droop in InGaN/GaN light-emitting diodes (LEDs) is proposed, where the primary nonradiative recombination mechanisms, including Shockley–Read–Hall (SRH), Auger and carrier leakage, are considered. A room-temperature external quantum efficiency (EQE) measurement was performed on our designed samples and analyzed by the new model. Owing to advantages over the common “[Formula: see text] model”, the “new model” is able to effectively extract recombination coefficients and calculate the leakage currents of the hole and electron. From this new model, we also found that hole leakage is distinct at low injection, while it disappears at high injection, which is contributed to the weak blocking effect of electron in quantum wells (QWs) at low injection.

Efficient green emission from (112¯2) InGaN∕GaN quantum wells on GaN microfacets probed by scanning near field optical microscopy

2007 ◽  
Vol 90 (26) ◽  
pp. 261912 ◽  
Author(s):  
Y. Kawakami ◽  
K. Nishizuka ◽  
D. Yamada ◽  
A. Kaneta ◽  
M. Funato ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Optical Microscopy ◽  
Near Field ◽  
Green Emission

scholarly journals Spatial and temporal luminescence dynamics in an InxGa1−xN single quantum well probed by near-field optical microscopy

2002 ◽  
Vol 81 (23) ◽  
pp. 4353-4355 ◽  
Author(s):  
Akio Kaneta ◽  
Koichi Okamoto ◽  
Yoichi Kawakami ◽  
Shigeo Fujita ◽  
Giichi Marutsuki ◽  
...  
Keyword(s):  
Quantum Well ◽  
Optical Microscopy ◽  
Near Field ◽  
Single Quantum ◽  
Single Quantum Well ◽  
Luminescence Dynamics
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