scholarly journals Light Guide Layer Thickness Optimization for Enhancement of the Light Extraction Efficiency of Ultraviolet Light–Emitting Diodes

2021 ◽  
Author(s):  
Zhi Ting Ye ◽  
Yuan Heng Cheng ◽  
Li Wei Hung ◽  
Kung Hsieh Hsu ◽  
Yu Chang Hu
Keyword(s):  
Layer Thickness ◽  
Extraction Efficiency ◽  
Light Guide ◽  
Light Emitting Diode ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Thickness Optimization ◽  
Optimal Thickness ◽  
Light Emitting ◽  
Uv C

Abstract Challenges related to deep-ultraviolet light-emitting diode substrates include material costs and lattice mismatch. Sapphire substrates are commonly used, although their high refractive index can result in the total internal reflection of light whereby some light is absorbed, reducing light extraction efficiency (LEE). In this study, we proposed an optimal thickness value of a sapphire substrate light guide layer through first-order optical design and used the optical simulation software Ansys SPEOS to assess and refine its effect on LEE. AlGaN ultraviolet-C light-emitting diode (UV-C LED) wafers with a substrate thickness of 150–700 μm were used. The simulation proceeded under a UV-C LED center wavelength of 275 nm to determine the optimal thickness of the light guide layer. Finally, the experimental results demonstrated that a light guide layer thickness of 150 μm resulted in a reference output power of 13.53 mW, and an increased thickness of 600 um resulted in output power of 20.58 mW. The LEE can therefore be increased by 1.52 times through light guide layer thickness optimization.

scholarly journals Light Guide Layer Thickness Optimization for Enhancement of the Light Extraction Efficiency of Ultraviolet Light–Emitting Diodes

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zhi Ting Ye ◽  
Yuan-Heng Cheng ◽  
Li-Wei Hung ◽  
Kung-Hsieh Hsu ◽  
Yu Chang Hu
Keyword(s):  
Layer Thickness ◽  
Extraction Efficiency ◽  
Light Guide ◽  
Optical Design ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Thickness Optimization ◽  
Light Emitting ◽  
First Order ◽  
Uv C

AbstractConsider material machinability and lattice mismatch sapphire as substrates for the ultraviolet-C light-emitting diodes (UV-C LEDs) are commonly used, but their high refractive index can result in the total internal reflection (TIR) of light whereby some light is absorbed, therefore caused reducing light extraction efficiency (LEE). In this study, we propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design which used the optical simulation software Ansys SPEOS to simulate and evaluate the light extraction efficiency. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. The simulation proceeded under a center wavelength of 275 nm to determine the optimal thickness design of the light guide layer. Finally, the experimental results demonstrated that the initial light guide layer thickness of 150 μm the reference output power of 13.53 mW, and an increased thickness of 600 um resulted in output power of 20.58 mW. The LEE can be increased by 1.52 times through light guide layer thickness optimization. We propose a method to optimize the thickness of a sapphire substrate light guide layer through first-order optical design. AlGaN UV-C LEDs wafers with a light guide layer thickness of 150–700 μm were used. Finally, the experimental results demonstrated that the LEE can be increased by 1.52 times through light guide layer thickness optimization.

Improved Light Extraction Efficiency of Light-Emitting Diode Grown on Nanoscale-Silicon-Dioxide-Patterned Sapphire Substrate

2020 ◽  
Vol 12 (5) ◽  
pp. 647-651 ◽  
Author(s):  
Young Hoon Sung ◽  
Jaemin Park ◽  
Eun-Seo Choi ◽  
Hee Chul Lee ◽  
Heon Lee
Keyword(s):  
Silicon Dioxide ◽  
Sapphire Substrate ◽  
Extraction Efficiency ◽  
Light Emitting Diode ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Sapphire Wafer ◽  
Luminescence Efficiency

A conical-shaped Si dioxide nano-pattern was employed to sapphire substrate in order to improve the light extraction efficiency of light-emitting diodes. The conical-shaped Si dioxide nano-patterns were fabricated on a 2-inch sapphire wafer using direct imprinting of hydrogen silsesquioxane material. A blue-LED structure was grown on conical-shaped silicon-dioxide nano-patterned sapphire substrates. Photoluminescence and electroluminescence measurements were used to confirm the effectiveness of the nanoscale Si oxide patterned sapphire. An improvement in the luminescence efficiency was observed when nanoscale Si oxide patterned sapphire substrate was used. 1.5 times higher PL intensity and 1.6 times higher EL intensity were observed for GaN LED structure grown on nanoscale Si oxide patterned sapphire, compared to LED structure grown on conventional flat sapphire wafer.

Integrating Surface Textures on ZnO Substrate for High Light Extraction Efficiency Light-Emitting Diode

2014 ◽  
Vol 118 (27) ◽  
pp. 14894-14898 ◽  
Author(s):  
Qinghong Zheng ◽  
Dan Zhang ◽  
Jin Huang ◽  
Yonghao Wang ◽  
Feng Huang
Keyword(s):  
Extraction Efficiency ◽  
Light Emitting Diode ◽  
High Light ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Emitting ◽  
Surface Textures

scholarly journals GEOMETRICAL ANALYSIS OF LIGHT-EMITTING DIODE FOR ENHANCING EXTRACTION EFFICIENCY

2020 ◽  
Vol 15 (6) ◽  
pp. 68-84
Author(s):  
ADAM SHAARI ◽  
◽  
AHMAD FAKHRURRAZI AHMAD NOORDEN ◽  
SAIFUL NAJMEE MOHAMAD ◽  
SUZAIRI DAUD ◽  
...  
Keyword(s):  
Contact Area ◽  
Indium Tin Oxide ◽  
Extraction Efficiency ◽  
Light Emitting Diode ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Current Spreading ◽  
Light Emitting ◽  
Uniform Current ◽  
Electrode Contact

A non-uniform current spreading in the current spreader can greatly reduce the efficiency of the light-emitting diode (LED). The effects of the electrode contact area to the spreading layer towards extraction efficiency of LED chips is analysed in analytical simulations. Length of current spreading and light extraction efficiency is analysed for variation of contact area. The contact area value is varied by changing the shape of the electrode and the value of width of contact area. The increase in contact area decreases light extraction efficiency as more light are absorbed by the bottom electrode surface. The effective current spreading length for Indium Tin Oxide (ITO) of thickness 300nm is 36.44µm. The 6 strips ‘fork’ design is the most optimum. The design has the most area for photons produced in active region to escape without reducing the area cover with current density. This enables the chip to has more extraction efficiency with more uniform current spreading.

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