High-output-power deep ultraviolet light-emitting diode assembly using direct bonding

Ichikawa, Michio; Fujioka, Akira; Kosugi, Takao; Endo, Shinya; Sagawa, Harunobu; Tamaki, Hiroto; Mukai, Takashi; Uomoto, Miyuki; Shimatsu, T.

doi:10.7567/apex.9.072101

Cited by 82 publications

(67 citation statements)

References 14 publications

(14 reference statements)

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“…In principle, an LED's external quantum efficiency is calculated using the following equation [35]: No. of photons emitted per second into free space No.…”

Section: Light Extraction Efficiencymentioning

confidence: 99%

Enhancing the Light-Extraction Efficiency of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes by Optimizing the Diameter and Tilt of the Aluminum Sidewall

et al. 2018

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To realize high-efficiency AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs), enhancing their light-extraction efficiency (LEE) is crucial. This paper proposes an aluminum-based sidewall reflector structure that could replace the conventional ceramic-based packaging method. We design optimization simulations and experimental results demonstrated the light power output could be enhanced 18.38% of DUV-LEDs packaged with the aluminum-based sidewall.

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“…In principle, an LED's external quantum efficiency is calculated using the following equation [35]: No. of photons emitted per second into free space No.…”

Section: Light Extraction Efficiencymentioning

confidence: 99%

Enhancing the Light-Extraction Efficiency of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes by Optimizing the Diameter and Tilt of the Aluminum Sidewall

et al. 2018

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“…The data are mainly for LED dies on planar sapphire from our group (colored). EQEs of LED dies from elsewhere (uncolored) using AlN substrates [17,18] and sapphire substrates [19][20][21] with a p-GaN contact layer are also shown. Solid uncolored symbols indicate the use of an AlN bulk substrate, where "■" indicates with encapsulation [17] and "◆" indicates no encapsulation.…”

Section: General Overviewmentioning

confidence: 99%

“…Meijo Univ. UV Craftory Nikkiso (JP) +FPG (TW) Sapphire CHT [13,[31][32][33][34][35][36][37][38][39][40] RIKEN NGK (JP) → 3 Dowa (JP) Panasonic (JP) Sapphire EM [19,[41][42][43][44][45] Nichia (JP) Sapphire [20,21,46] Toyoda Gosei (JP) Sapphire FBH 2 TU Berlin UV Photonics [47][48][49] Siemens AG DE) Bioraytron HPL (TW) +Epileds (TW) Sapphire…”

Section: Seti Nitekmentioning

confidence: 99%

A Review of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes on Sapphire

Nagasawa¹,

Hirano²

2018

Applied Sciences

184

111

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This paper reviews the progress of AlGaN-based deep-ultraviolet (DUV) light emitting diodes (LEDs), mainly focusing in the work of the authors’ group. The background to the development of the current device structure on sapphire is described and the reason for using a (0001) sapphire with a miscut angle of 1.0° relative to the m-axis is clarified. Our LEDs incorporate uneven quantum wells (QWs) grown on an AlN template with dense macrosteps. Due to the low threading dislocation density of AlGaN and AlN templates of about 5 × 108/cm2, the number of nonradiative recombination centers is decreased. In addition, the uneven QW show high external quantum efficiency (EQE) and wall-plug efficiency, which are considered to be boosted by the increased internal quantum efficiency (IQE) by enhancing carrier localization adjacent to macrosteps. The achieved LED performance is considered to be sufficient for practical applications. The advantage of the uneven QW is discussed in terms of the EQE and IQE. A DUV-LED die with an output of over 100 mW at 280–300 nm is considered feasible by applying techniques including the encapsulation. In addition, the fundamental achievements of various groups are reviewed for the future improvements of AlGaN-based DUV-LEDs. Finally, the applications of DUV-LEDs are described from an industrial viewpoint. The demonstrations of W/cm2-class irradiation modules are shown for UV curing.

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“…Crystal IS developed efficient 265 nm LEDs on bulk AlN substrates fabricated by a sublimation method [35,36], and Tokuyama developed UVC LEDs on a thick transparent AlN layer grown, also on bulk AlN substrates, by hydride vapor phase epitaxy (HVPE) [37][38][39][40]. Nichia has developed high wall-plug efficiency (WPE) UVC LEDs [41,42] using a lens bonding technique [42]. Also, M. Kneissl's group in the Technical Figure 3.…”

Section: Research Background Of Uv Ledsmentioning

confidence: 99%

Recent Progress in AlGaN Deep-UV LEDs

Hasegawa¹

2018

Light-Emitting Diode - An Outlook on the Empirical Features and Its Recent Technological Advancements

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AlGaN deep ultraviolet light-emitting diodes (DUV LEDs) have a wide variety of potential applications, including uses for sterilization, water purification, and UV curing and in the medical and biochemistry fields. However, the wall-plug efficiency (WPE) of AlGaN DUV LEDs remains below values. We have developed crystal growth techniques for wide-bandgap AlN and AlGaN and, using these techniques, fabricated DUV LEDs in the 220-350 nm-band. Considerable increases in the internal quantum efficiency (IQE) of AlGaN quantum wells (QW) were achieved by developing low-threading dislocation density (TDD) AlN grown on sapphire substrates. The electron injection efficiency (EIE) was substantially increased by introducing a multi-quantum barrier (MQB) as an electronblocking layer (EBL). The light-extraction efficiency (LEE) was also improved by using a transparent p-AlGaN contact layer, a highly reflective (HR) p-type electrode, and an AlN template fabricated on a patterned sapphire substrate (PSS). Further improvements were made by implementing a reflective photonic crystal (PhC) p-contact layer. We demonstrated a record external quantum efficiency (EQE) of 20.3% for an AlGaN UVC-LED.

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High-output-power deep ultraviolet light-emitting diode assembly using direct bonding

Cited by 82 publications

References 14 publications

Enhancing the Light-Extraction Efficiency of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes by Optimizing the Diameter and Tilt of the Aluminum Sidewall

Enhancing the Light-Extraction Efficiency of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes by Optimizing the Diameter and Tilt of the Aluminum Sidewall

A Review of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes on Sapphire

Recent Progress in AlGaN Deep-UV LEDs

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