150 mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265 nm

Inoue, Shin‐ichiro; Tamari, Naoki; Taniguchi, Masateru

doi:10.1063/1.4978855

Cited by 182 publications

(123 citation statements)

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“…A maximum light extraction enhancement of 196% was obtained in 265-nm LEDs with the hybrid structure in comparison to that of a flat surface device. To enable high-output and high-volume fabrication, they further presented 265-nm DUV LEDs with largearea nanoimprinted AlN nanophotonic structures, 7 which showed wider near-field emitting areas, stronger far-field extracted light intensities, and an approximately 20-fold increase in LOP compared with a conventional flat-surface LED.…”

Section: Substrate Surface Rougheningmentioning

confidence: 99%

“…[2][3][4][5] Recently, Takano et al 6 claimed to obtain deep-UV (DUV) LEDs with a maximum external quantum efficiency (EQE) of 20.3% at 275 nm. Inoue et al 7 reported a 265-nm single-chip LED with a record continuous-wave output power in excess of 150 mW (corresponding EQE: 3.9%) for an injection current of 850 mA. However, the typical EQE of DUV LEDs is still in the single-digit percentage range and the output power in a couple of milliwatts, depending on the wavelength.…”

Section: Introductionmentioning

confidence: 99%

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Enhancing the light extraction of AlGaN-based ultraviolet light-emitting diodes in the nanoscale

et al. 2018

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, "Enhancing the light extraction of AlGaN-based ultraviolet light-emitting diodes in the nanoscale," J. Nanophoton. 12(4), 043510 (2018), doi: 10.1117/1.JNP.12.043510. Abstract. AlGaN-based ultraviolet light-emitting diodes (UV LEDs) are promising nextgeneration UV sources for a wide variety of applications. The state-of-the-art AlGaN-based UV LEDs exhibit much lower output power and external quantum efficiency than highly commercialized GaN visible LEDs. One key issue for UV LEDs is the poor light-extraction efficiency. We have reviewed the recent progress in the light extraction approaches for AlGaNbased UV LEDs, including the highly reflective techniques, and the surface/interface modification for total internal reflection mitigating. Moreover, AlGaN-based UV LEDs in the nanoscale structures, such as nanopillar, nanorod, and nanowire structures, are also discussed.

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Section: Substrate Surface Rougheningmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhancing the light extraction of AlGaN-based ultraviolet light-emitting diodes in the nanoscale

et al. 2018

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“…DUV LEDs generally employ flip-chip configuration for efficient heat dissipation and light extraction [21][22][23][24]. In spite of this, flip-chip designs still suffer from a relatively low extraction efficiency caused by the dominant transverse magnetic (TM)-polarized light emission, which propagates mainly in the lateral direction [25].…”

Section: Device Design For Improved Performance Of Group Iii-nitride mentioning

confidence: 99%

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

et al. 2017

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Abstract:We overview recent progress in growth aspects of group III-nitride heterostructures for deep ultraviolet (DUV) light-emitting diodes (LEDs), with particular emphasis on the growth approaches for attaining high-quality AlN and high Al-molar fraction AlGaN. The discussion commences with the introduction of the current status of group III-nitride DUV LEDs and the remaining challenges. This segues into discussion of LED designs enabling high device performance followed by the review of advances in the methods for the growth of bulk single crystal AlN intended as a native substrate together with a discussion of its UV transparency. It should be stated, however, that due to the high-cost of bulk AlN substrates at the time of writing, the growth of DUV LEDs on foreign substrates such as sapphire still dominates the field. On the deposition front, the heteroepitaxial growth approaches incorporate high-temperature metal organic chemical vapor deposition (MOCVD) and pulsed-flow growth, a variant of MOCVD, with the overarching goal of enhancing adatom surface mobility, and thus epitaxial lateral overgrowth which culminates in minimization the effect of lattice-and thermal-mismatches. This is followed by addressing the benefits of pseudomorphic growth of strained high Al-molar fraction AlGaN on AlN. Finally, methods utilized to enhance both p-and n-type conductivity of high Al-molar fraction AlGaN are reviewed.

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“…The 255 nm DUV LEDs with a sapphire lens fabricated using the surface activated bonding method have shown a light extraction efficiency enhancement of 2.8 times when compared to a reference LED lacking the lens, and an EQE of 4.56% was achieved. Inoue et al [5,24] have developed large-area AlN nanophotonic structures to enhance the light extraction efficiency of DUV LEDs. The LEDs with the nanoimprinted AlN nanophotonic structures exhibit wider near-field emitting areas, stronger far-field extracted light intensities, and an approximately 20-fold increase in the output power when compared with a conventional flat-surface DUV LED.…”

Section: Device Design For Improved Performance Of Group Iii-nitrde Dmentioning

confidence: 99%

“…A CW output power in excess of 150 mW for an injection current of 850 mA has been achieved in the nanoimprinted UVC LEDs emitting at 265 nm. [24] Nagai et al [25][26][27] have investigated the feasibility of encapsulation of AlGaN-based DUV LEDs with silicone resin and with polymerized perfluoro-4-vinyloxy-1-butene (BVE)-based fluorine polymers having -COOCH3 ends in comparison with fluorine polymers having terminal ends of -CF3 and -COOH in order to enhance light extraction. Serious damage to the electrode metal was observed, except for the BVE-based polymer with -CF3 ends.…”

Section: Device Design For Improved Performance Of Group Iii-nitrde Dmentioning

confidence: 99%

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

Ding¹,

Avrutin²,

Özgür³

et al. 2017

Preprint

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Abstract:We overview recent progress in growth aspects of group III-nitride heterostructures for deep ultraviolet (DUV) light-emitting diodes (LEDs), with particular emphasis on the growth approaches for attaining high-quality AlN and high Al-molar fraction AlGaN. The discussion commences with the introduction of the current status of group III-nitride DUV LEDs and the remaining challenges. This segues into discussion of LED designs enabling high device performance followed by the review of advances in the methods for the growth of bulk single crystal AlN intended as a native substrate together with a discussion of its UV transparency. It should be stated, however, that due to the high-cost of bulk AlN substrates at the time of this writing, the growth of DUV LEDs on foreign substrates such as sapphire still dominates the field. On the deposition front, the heteroepitaxial growth approaches incorporate high-temperature metal organic chemical vapor deposition (MOCVD) and pulsed-flow growth, a variant of MOCVD, with the overarching goal of enhancing adatom surface mobility, and thus epitaxial lateral overgrowth which culminates in minimization the effect of lattice-and thermal-mismatches. This is followed by addressing the benefits of pseudomorphic growth of strained high Al-molar fraction AlGaN on AlN. Finally, methods utilized to enhance both p-and n-type conductivity of high Al-molar fraction AlGaN are reviewed.

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150 mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265 nm

Cited by 182 publications

References 18 publications

Enhancing the light extraction of AlGaN-based ultraviolet light-emitting diodes in the nanoscale

Enhancing the light extraction of AlGaN-based ultraviolet light-emitting diodes in the nanoscale

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

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