A Novel Liquid Packaging Structure of Deep-Ultraviolet Light-Emitting Diodes to Enhance the Light-Extraction Efficiency

Kang, Chieh Yu; Lin, Chih Hao; Wu, Tingzhu; Lee, Po-Tsung; Chen, Zhong; Kuo, Hao‐Chung

doi:10.3390/cryst9040203

Cited by 24 publications

(16 citation statements)

References 23 publications

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“…For example, Prof. Hao-Chung Kuo's group of National Chiao Tung University studied the LEE of new packaging materials. Through the addition of silicone oil, which had a refractive index of 1.487, to adjust the refractive index changes inside and outside the UV chip, and rational selection of the material of the reflector, to adjust reflectivity, the light output power of the UV LED was increased by 70.7% compared with that of a traditional package, whereas the thermal resistance was reduced by 30.3% [82]. Meanwhile, Wang et al proposed a new encapsulation structure for aluminum nitride-based DUV-LEDs and eutectic flip chips containing polydimethylsiloxane (PDMS) fluid doped with SiO 2 nanoparticles (NPs) with a UV-transparent quartz hemispherical glass cover.…”

Section: Problem Of Light Extraction Efficiencymentioning

confidence: 99%

Perspectives on UVC LED: Its Progress and Application

et al. 2021

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High-quality epitaxial layers are directly related to internal quantum efficiency. The methods used to design such epitaxial layers are reviewed in this article. The ultraviolet C (UVC) light-emitting diode (LED) epitaxial layer structure exhibits electron leakage; therefore, many research groups have proposed the design of blocking layers and carrier transportation to generate high electron–hole recombination rates. This also aids in increasing the internal quantum efficiency. The cap layer, p-GaN, exhibits high absorption in deep UV radiation; thus, a small thickness is usually chosen. Flip chip design is more popular for such devices in the UV band, and the main factors for consideration are light extraction and heat transportation. However, the choice of encapsulation materials is important, because unsuitable encapsulation materials will be degraded by ultraviolet light irradiation. A suitable package design can account for light extraction and heat transportation. Finally, an atomic layer deposition Al2O3 film has been proposed as a mesa passivation layer. It can provide a low reverse current leakage. Moreover, it can help increase the quantum efficiency, enhance the moisture resistance, and improve reliability. UVC LED applications can be used in sterilization, water purification, air purification, and medical and military fields.

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Section: Problem Of Light Extraction Efficiencymentioning

confidence: 99%

Perspectives on UVC LED: Its Progress and Application

et al. 2021

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“…Kang et al proposed a liquid package LED structure that not only improved the light output efficiency, but also reduced the thermal resistance by approximately 30% [ 12 ]. Lan Hai et al studied the package thermal resistance of different COB substrates, and optimized the COB LED package to enhance heat dissipation by using materials with high thermal conductivity or reducing the thickness of the bonding layer [ 13 ]. However, only a few studies on the interaction between packaging density and different COB packaging substrates have been conducted, especially regarding the thermal performance of the COB packaging of deep UV LEDs.…”

Section: Introductionmentioning

confidence: 99%

Influence on temperature distribution of COB deep UV LED due to different packaging density and substrate type

Xia

Liang

et al. 2021

Optik

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“…In this regard, Chieh-Yu Kang proposed a new type of DUV LED liquid packaging structure can achieve LEE improvements. Chien Chun Lu demonstrated the higher and more reliable LEE of UV-C LEDs with a quartz-based hermetic package [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

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

Cheng

Hung³

et al. 2021

Nanoscale Res Lett

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Consider 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.

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A Novel Liquid Packaging Structure of Deep-Ultraviolet Light-Emitting Diodes to Enhance the Light-Extraction Efficiency

Cited by 24 publications

References 23 publications

Perspectives on UVC LED: Its Progress and Application

Perspectives on UVC LED: Its Progress and Application

Influence on temperature distribution of COB deep UV LED due to different packaging density and substrate type

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

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