scholarly journals Optimized Aluminum Reflector for Enhancement of UVC Cathodoluminescence Based-AlGaN Materials with Carbon Nanotube Field Emitters

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4025
Author(s):  
Manoj Kumar Chandra Mohan ◽  
Sang Kyun Shim ◽  
June Key Lee ◽  
Nakwon Jang ◽  
Naesung Lee ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Power Efficiency ◽  
Extraction Efficiency ◽  
Light Output ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Sources ◽  
Field Emitters ◽  
Ultraviolet C ◽  
Far Ultraviolet

The far ultraviolet C (UVC) light sources based on carbon nanotube (CNT) field emitters as excitation sources have become promising light sources for sterilization, disinfection, and water purification. However, the low light extraction efficiency of UVC–CNT light sources still hinders the practical application of these structures. Herein, we report an optimized aluminum (Al) reflector to enhance the light extraction efficiency of UVC–CNT light sources. Optical analysis of UVC-CNT light sources covered by the Al reflectors with various thicknesses ranging from 30 to 150 nm was performed to realize the optimized reflector. The UVC-CNT light sources exhibit the highest light extraction efficiency when the Al reflector layer has an optimized thickness of 100 nm. For comparison, the cathodoluminescence (CL) spectra were recorded for UVC–CNT light sources with and without the optimized Al reflector. The measured light output power and the estimated power efficiency of the UVC–CNT light-source-tube with Al reflector were enhanced by about 27 times over the reference. This enhancement is mainly attributed to the outstanding reflection effect of the Al reflector.

scholarly journals Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Nanomaterials ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 319 ◽  
Author(s):  
Bin Tang ◽  
Jia Miao ◽  
Yingce Liu ◽  
Hui Wan ◽  
Ning Li ◽  
...  
Keyword(s):  
Total Internal Reflection ◽  
Flip Chip ◽  
Extraction Efficiency ◽  
Light Output ◽  
Cost Effective ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Output Power ◽  
Light Emitting ◽  
Air Interface

Current solutions for improving the light extraction efficiency of flip-chip light-emitting diodes (LEDs) mainly focus on relieving the total internal reflection at sapphire/air interface, but such methods hardly affect the epilayer mode photons. We demonstrated that the prism-structured sidewall based on tetramethylammonium hydroxide (TMAH) etching is a cost-effective solution for promoting light extraction efficiency of flip-chip mini-LEDs. The anisotropic TMAH etching created hierarchical prism structure on sidewall of mini-LEDs for coupling out photons into air without deteriorating the electrical property. Prism-structured sidewall effectively improved light output power of mini-LEDs by 10.3%, owing to the scattering out of waveguided light trapped in the gallium nitride (GaN) epilayer.

scholarly journals SILAR-Based Application of Various Nanopillars on GaN-Based LED to Enhance Light-Extraction Efficiency

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. C. Shei
Keyword(s):  
Output Power ◽  
Indium Tin Oxide ◽  
Extraction Efficiency ◽  
Light Output ◽  
Contact Layer ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Operating Voltage ◽  
Light Output Power ◽  
The Difference

We reported the various nanopillars on GaN-based LED to enhance light-extraction efficiency prepared by successive ionic layer adsorption and reaction method (SILAR). Indium tin oxide (ITO) with thickness of 1 μm as transparent contact layer was grown to improve the electrical characteristics of the LEDs, including series resistance and operating voltage. SILAR-deposition ZnO nanoparticles on SiO2were used as etching nanomasks. Multiple nanopillars were simultaneously formed on overall surfaces of ITO p- and n-GaN by ICP etching. The proposed GaN-based LEDs with nanopillars increase light output power by 7%–20.3% (at 20 mA) over that of regular GaN-based LEDs. The difference in light output power can be attributed to differences in materials and shapes of nanopillars, resulting in a reduction in Fresnel reflection by the roughened surface of GaN-based LEDs.

scholarly journals Investigation of Photonic-Crystal-Structured p-GaN Nanorods Fabricated by Polystyrene Nanosphere Lithography Method to Improve the Light Extraction Efficiency of InGaN/GaN Green Light-Emitting Diodes

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2200
Author(s):  
Po-Hsun Lei ◽  
Po-Chun Yang ◽  
Po-Chun Huang
Keyword(s):  
Photonic Crystal ◽  
Spin Coating ◽  
Light Emitting Diodes ◽  
Extraction Efficiency ◽  
Light Output ◽  
Green Light ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Emitting ◽  
Green Leds

We fabricated the photonic-crystal-structured p-GaN (PC-structured p-GaN) nanorods using the modified polystyrene nanosphere (PS NS) lithography method for InGaN/GaN green light-emitting diodes (LEDs) to enhance the light extraction efficiency (LEE). A modified PS NS lithography method including two-times spin-coating processes and the post-spin-coating heating treatment was used to obtain a self-assembly close-packed PS NS array of monolayer as a mask and then a partially dry etching process was applied to PS NS, SiO2, and p-GaN to form PC-structured p-GaN nanorods on the InGaN/GaN green LEDs. The light output intensity and LEE of InGaN/GaN green LEDs with the PC-structured p-GaN nanorods depend on the period, diameter, and height of PC-structured p-GaN nanorods. RSoft FullWAVE software based on the three-dimension finite-difference time-domain (FDTD) algorithm was used to calculate the LEE of InGaN/GaN green LEDs with PC-structured p-GaN nanorods of the varied period, diameter, and height. The optimal period, diameter, and height of PC-structured p-GaN nanorods are 150, 350, and 110 nm. The InGaN/GaN green LEDs with optimal PC-structured p-GaN nanorods exhibit an enhancement of 41% of emission intensity under the driving current of 20 mA as compared to conventional LED.

ZnO Nano-arrays on High Power Blue LED Chip for Enhanced Light Extraction Efficiency

2012 ◽  
Vol 27 (7) ◽  
pp. 716-720
Author(s):  
Bing XU ◽  
Jun-Liang ZHAO ◽  
Jian-Ming ZHANG ◽  
Xiao-Wei SUN ◽  
Fu-Wei ZHUGE ◽  
...  
Keyword(s):  
High Power ◽  
Extraction Efficiency ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Blue Led
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