Light output enhancement of GaN-based light-emitting diodes by maskless surface roughening

2015 ◽  
Vol 139 ◽  
pp. 39-42 ◽  
Author(s):  
Yibin Yang ◽  
Yuan Ren ◽  
Yangxiang Chen ◽  
Minggang Liu ◽  
Weijie Chen ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Output ◽  
Surface Roughening ◽  
Light Emitting

Study on Light Intensity Enhancement of ZnO/ITO/P-GaN Light-Emitting Diodes

2011 ◽  
Vol 130-134 ◽  
pp. 4084-4087
Author(s):  
Hsing Cheng Chang ◽  
Ya Hui Chen ◽  
San Shan Hung ◽  
Chi Chih Lai ◽  
Chein Chuan Hung ◽  
...  
Keyword(s):  
Light Intensity ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Zno Nanorods ◽  
Light Output ◽  
Surface Roughening ◽  
Light Emitting ◽  
Intensity Enhancement ◽  
Great Performance ◽  
Output Efficiency

Light intensity enhancement of GaN-based blue light-emitting diodes (LEDs) is performed using different surface roughening technologies. Three roughening technologies are applied that contain surface roughening of p-GaN, textured indium tin oxide (ITO) on roughened p-GaN, and growing ZnO nanorods on textured ITO/p-GaN. A roughened p-GaN surface was grown on the c-plane sapphire substrate at temperature 800 °C. The morphologies of the textured LEDs with roughness in the range from 9.67 nm to 51.13 nm were observed. The light output efficiency of LED with roughened ITO layer is increased up to 73.8 %. Different dimensions of LEDs can be driven by constant injection current 20 mA without increasing threshold voltage, and larger size of ZnO/ITO/p-GaN LED shows higher luminance intensity. The LEDs with ZnO nanorods on roughened ITO/GaN have shown great performance to enhance the power conversion efficiency.

Enhanced Light Output of GaN-Based Vertical-Structured Light-Emitting Diodes With Two-Step Surface Roughening Using KrF Laser and Chemical Wet Etching

2010 ◽  
Vol 22 (17) ◽  
pp. 1318-1320 ◽  
Author(s):  
Wei-Chi Lee ◽  
Shui-Jinn Wang ◽  
Kai-Ming Uang ◽  
Tron-Min Chen ◽  
Der-Ming Kuo ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Structured Light ◽  
Light Output ◽  
Wet Etching ◽  
Surface Roughening ◽  
Light Emitting ◽  
Krf Laser

Low-Temperature Operation of Green, Blue and UV InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes

2003 ◽  
Vol 764 ◽  
Author(s):  
X. A. Cao ◽  
S. F. LeBoeuf ◽  
J. L. Garrett ◽  
A. Ebong ◽  
L. B. Rowland ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Localized States ◽  
Multiple Quantum ◽  
Nonradiative Recombination ◽  
Light Emitting ◽  
Temperature Range ◽  
Green Leds

Absract:Temperature-dependent electroluminescence (EL) of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with peak emission energies ranging from 2.3 eV (green) to 3.3 eV (UV) has been studied over a wide temperature range (5-300 K). As the temperature is decreased from 300 K to 150 K, the EL intensity increases in all devices due to reduced nonradiative recombination and improved carrier confinement. However, LED operation at lower temperatures (150-5 K) is a strong function of In ratio in the active layer. For the green LEDs, emission intensity increases monotonically in the whole temperature range, while for the blue and UV LEDs, a remarkable decrease of the light output was observed, accompanied by a large redshift of the peak energy. The discrepancy can be attributed to various amounts of localization states caused by In composition fluctuation in the QW active regions. Based on a rate equation analysis, we find that the densities of the localized states in the green LEDs are more than two orders of magnitude higher than that in the UV LED. The large number of localized states in the green LEDs are crucial to maintain high-efficiency carrier capture at low temperatures.

scholarly journals Improved Performance of GaN-Based Light-Emitting Diodes Grown on Si (111) Substrates with NH3 Growth Interruption

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 399
Author(s):  
Sang-Jo Kim ◽  
Semi Oh ◽  
Kwang-Jae Lee ◽  
Sohyeon Kim ◽  
Kyoung-Kook Kim
Keyword(s):  
Buffer Layer ◽  
Light Emitting Diodes ◽  
Defect Density ◽  
Strain Relaxation ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Multiple Quantum ◽  
Light Emitting ◽  
Growth Interruption ◽  
Aln Buffer

We demonstrate the highly efficient, GaN-based, multiple-quantum-well light-emitting diodes (LEDs) grown on Si (111) substrates embedded with the AlN buffer layer using NH3 growth interruption. Analysis of the materials by the X-ray diffraction omega scan and transmission electron microscopy revealed a remarkable improvement in the crystalline quality of the GaN layer with the AlN buffer layer using NH3 growth interruption. This improvement originated from the decreased dislocation densities and coalescence-related defects of the GaN layer that arose from the increased Al migration time. The photoluminescence peak positions and Raman spectra indicate that the internal tensile strain of the GaN layer is effectively relaxed without generating cracks. The LEDs embedded with an AlN buffer layer using NH3 growth interruption at 300 mA exhibited 40.9% higher light output power than that of the reference LED embedded with the AlN buffer layer without NH3 growth interruption. These high performances are attributed to an increased radiative recombination rate owing to the low defect density and strain relaxation in the GaN epilayer.

Improved Light Output Power of GaN-Based Light-Emitting Diodes Using Double Photonic Quasi-Crystal Patterns

2009 ◽  
Vol 30 (11) ◽  
pp. 1152-1154 ◽  
Author(s):  
Hung-Wen Huang ◽  
Chung-Hsiang Lin ◽  
Zhi-Kai Huang ◽  
Kang-Yuan Lee ◽  
Chang-Chin Yu ◽  
...  
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Output Power ◽  
Light Emitting

scholarly journals High-Power GaN-Based Vertical Light-Emitting Diodes on 4-Inch Silicon Substrate

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1178 ◽  
Author(s):  
Qiang Zhao ◽  
Jiahao Miao ◽  
Shengjun Zhou ◽  
Chengqun Gui ◽  
Bin Tang ◽  
...  
Keyword(s):  
High Power ◽  
Silicon Substrate ◽  
Flip Chip ◽  
Heat Dissipation ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Current Spreading ◽  
Light Emitting ◽  
Fabry Perot ◽  
Lift Off

We demonstrate high-power GaN-based vertical light-emitting diodes (LEDs) (VLEDs) on a 4-inch silicon substrate and flip-chip LEDs on a sapphire substrate. The GaN-based VLEDs were transferred onto the silicon substrate by using the Au–In eutectic bonding technique in combination with the laser lift-off (LLO) process. The silicon substrate with high thermal conductivity can provide a satisfactory path for heat dissipation of VLEDs. The nitrogen polar n-GaN surface was textured by KOH solution, which not only improved light extract efficiency (LEE) but also broke down Fabry–Pérot interference in VLEDs. As a result, a near Lambertian emission pattern was obtained in a VLED. To improve current spreading, the ring-shaped n-electrode was uniformly distributed over the entire VLED. Our combined numerical and experimental results revealed that the VLED exhibited superior heat dissipation and current spreading performance over a flip-chip LED (FCLED). As a result, under 350 mA injection current, the forward voltage of the VLED was 0.36 V lower than that of the FCLED, while the light output power (LOP) of the VLED was 3.7% higher than that of the FCLED. The LOP of the FCLED saturated at 1280 mA, but the light output saturation did not appear in the VLED.

Size-dependent light output, spectral shift, and self-heating of 400 nm InGaN light-emitting diodes

2010 ◽  
Vol 107 (1) ◽  
pp. 013103 ◽  
Author(s):  
Zheng Gong ◽  
Shirong Jin ◽  
Yujie Chen ◽  
Jonathan McKendry ◽  
David Massoubre ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Output ◽  
Spectral Shift ◽  
Light Emitting ◽  
Size Dependent ◽  
Self Heating

scholarly journals Light Extraction Enhancement of InGaN Based Micro Light-Emitting Diodes with Concave-Convex Circular Composite Structure Sidewall

2019 ◽  
Vol 9 (17) ◽  
pp. 3458 ◽  
Author(s):  
Tan ◽  
Zhou ◽  
Hu ◽  
Wang ◽  
Yao
Keyword(s):  
Composite Structure ◽  
Inductively Coupled Plasma ◽  
Total Internal Reflection ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Electrical Characteristics ◽  
Light Emitting ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Output Characteristics

We demonstrate that the concave-convex circular composite structure sidewall prepared by inductively coupled plasma (ICP) etching is an effective approach to increase the light efficiency without deteriorating the electrical characteristics for micro light-emitting diodes (LEDs). The saturated light output power of the device using the concave-convex circular composite structure sidewalls with a radius of 2 μm is 39.75 mW, an improvement of 7.2% compared with that of the device using flat sidewalls. The enhanced light output characteristics are primarily attributed to the increased photon emitting due by decreasing the total internal reflection without losing the active region area.

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