(Invited) High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room Temperature Bonding

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

doi:10.1149/07509.0053ecst

Cited by 10 publications

(13 citation statements)

References 21 publications

(36 reference statements)

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“…Ichikawa et al [27] reported the application of hemispherical sapphire lenses bonded to the substrates of DUV LED chips to enhance the light extraction efficiency. The 255 nm DUV LEDs with a sapphire lens fabricated using the surface activated bonding method showed 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.…”

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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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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show abstract

“…[1] Ichikawa et al [23] have reported the application of hemispherical sapphire lenses bonded to the substrates of DUV LED chips to enhance the light extraction efficiency. 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.…”

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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“…Deep-UV light with an emission wavelength below 290 nm can rapidly inactivate the deoxyribonucleic acid of virus and bacteria [4,5]; however, the light-emission efficiency (LEE) of deep-UV LEDs is considerably lower than that of low-pressure mercury lamps. The wall-plug efficiency of mass-produced deep-UV LEDs is a maximum of 10% because of the UV light absorption of the p-type gallium nitride (GaN) contact layer [6][7][8]. A p-type GaN contact layer is used Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s).…”

Section: Introductionmentioning

confidence: 99%

Improvement of Algan Homoepitaxial Tunnel Junction Deep-UV Light-Emitting Diodes by Controlling the Growth of N-Type Algan and Polycrystalline Mgzno/Al Electrodes

Nagata¹,

Matsubara²,

Saito³

et al. 2023

Preprint

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Deep-ultraviolet (UV) light-emitting diodes (LEDs) based on AlGaN crystals have low light-emission efficiency; therefore, there is a need to improve this light-emission efficiency for a wide range of applications such as water and air sterilizations. UV-light-transparent device structures are considered one of the many solutions toward increasing light output power. To this end, the present study focused on developing a transparent AlGaN-based tunnel junction (TJ) as the anode of a deep-UV LED. Deep-UV LEDs composed of n+/p+-type AlGaN TJs were fabricated under the growth condition that reduced the carrier compensation in the n+-type AlGaN layers. The operating voltage was 10.8 V under the direct current (DC) operation of 63 A/cm2. In addition, magnesium zinc oxide (MgZnO)/Al reflective electrodes were fabricated to enhance the output power of the AlGaN homoepitaxial TJ LED. The output power was 57.3 mW under a DC operation of 63 A/cm2, and it was 1.7 times higher than that realized using the conventional Ti/Al electrodes. The combination of the AlGaN-based TJ and MgZnO/Al reflective contact allows further improvement of the light output power. This study confirms that the AlGaN TJ is a promising UV-transmittance structure that can obtain a high light-extraction efficiency.

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(Invited) High Output Power Deep Ultraviolet Light-Emitting Diodes with Hemispherical Lenses Fabricated Using Room Temperature Bonding

Cited by 10 publications

References 21 publications

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

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

Improvement of Algan Homoepitaxial Tunnel Junction Deep-UV Light-Emitting Diodes by Controlling the Growth of N-Type Algan and Polycrystalline Mgzno/Al Electrodes

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