High‐performance UV emitter grown on high‐crystalline‐quality AlGaN underlying layer

Tsuzuki, Hirotoshi; Mori, Fumiaki; Takeda, Kenta; Ichikawa, Tomoki; Iwaya, Motoaki; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu; Yoshida, Harumasa; Kuwabara, Masakazu; Yamashita, Yoshifumi; Kan, Hirofumi

doi:10.1002/pssa.200880784

Cited by 50 publications

(43 citation statements)

References 13 publications

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“…Previously, we reported that the crystalline quality of AlGaN on AlN was much improved by growing AlN on a grooved AlN template [1]. The highest efficiency UV LEDs [2] and also UV laser diodes (UV LDs) [3] can be successfully fabricated using a grooved AlN template. However, this grooved template technology requires an additional etching process, which reduces the yield of the devices and increases the process cost.…”

Section: Introductionmentioning

confidence: 98%

Growth of low‐dislocation‐density AlGaN using Mg‐doped AlN underlying layer

Asai

Nonaka

Ban

et al. 2010

Phys. Status Solidi (c)

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We report on a new technology for growing low‐dislocation‐density AlGaN in which a Mg‐doped AlN underlying layer is used. By growing AlxGa1‐xN on AlN:Mg with AlN molar fractions x of 0.3, 0.5 and 0.7, the density of misfit dislocations is much reduced compared with that in the case of growing AlGaN on undoped AlN. In addition, the surface becomes atomically flat. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Section: Introductionmentioning

confidence: 98%

Growth of low‐dislocation‐density AlGaN using Mg‐doped AlN underlying layer

Asai

Nonaka

Ban

et al. 2010

Phys. Status Solidi (c)

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“…The growth temperature was over 1000 o C for AlGaN layers and up to 1400 o C for AlN. The growth pressure was 6.6×10 4 Pa. During the Al 0.25 Ga 0.75 N growth, 30 μmol/min TMGa, 13 μmol/min TMAl, and 60 μmol/min ammonia were typically injected into the MOVPE reactor. Ridge stripe laser structures were processed from the above two wafers.…”

Section: Methodsmentioning

confidence: 99%

“…We have reported UV LDs on grooved AlGaN templates prepared by heteroepitaxial lateral overgrowth (ELO) [6] and/or hetero-facet-controlled ELO [7]. In this paper, we report two issues related to these UV LD structures.…”

Section: CMmentioning

confidence: 96%

“…For instance, the external quantum efficiency of AlGaN/GaN UV LEDs is 6.7% in Ref. [4]. Also, the pulsed operation at a lasing wavelength of 336 nm has been reported [3].…”

Section: CMmentioning

confidence: 98%

“…Nitridebased UV emitters are becoming key devices for a number of applications, such as biochemical photonics, material processing, and laser knives. So far, group-III-nitridebased UV light-emitting diodes (LEDs) and UV laser diodes (LDs) have been reported by several groups [1][2][3][4]. For instance, the external quantum efficiency of AlGaN/GaN UV LEDs is 6.7% in Ref.…”

Section: CMmentioning

confidence: 98%

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Reduction in threshold current density of 355 nm UV laser diodes

Nagata

Takeda

Nonaka

et al. 2011

Phys. Status Solidi C

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We have investigated the characteristics of 355 nm UV laser diodes. Two laser diode structures were prepared on a grooved AlGaN template as well as on a flat AlGaN template. The threading dislocation densities on the grooved and flat AlGaN were 2.5×108 cm‐2 and 6.5×109 cm‐2, respectively. The threshold current density of the laser diode on the grooved AlGaN was 6 kA/cm2, while no lasing was observed from the laser diode on the flat AlGaN. We also estimated the internal quantum efficiency as well as the injection efficiency in the UV laser diode structures by considering internal quantum efficiency of both optical and electrical excitation. At a carrier density of 1.2×1019 cm‐3, the internal quantum efficiency of the laser diode structure on the grooved AlGaN was about 50%. This is twice that of the laser diode on the flat AlGaN. At the same time, the internal quantum efficiency estimated from the optical excitation also reached about 50%, even at a carrier density of 3×1018 cm‐3. This implies that the injection efficiency in our UV laser diode structure was only 25%. Improving the injection efficiency should be effective for significantly reducing the threshold current density. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

Liang

Sun

2022

Adv Materials Technologies

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AlGaN‐based deep ultraviolet light‐emitting diodes (UV LEDs) have gained rapidly growing attention due to their wide applications in water purification, air disinfection, and sensing as well as optical communication. Moreover, deep UV radiation has been verified as one of effective way to inactivate COVID‐19. However, although numerous efforts have been made in deep UV LED chips, the reported highest external quantum efficiency (EQE) of them is 20.3%, which is far lower than that of visible LEDs. The EQE of commercial packaged AlGaN‐based deep UV LEDs is usually lower than 5%, which will cause serious reliability problems as well. Therefore, it is very urgent to improve EQE and reliability of the devices from packaging level. In this review, a systematical summarization about the packaging technologies of AlGaN‐based deep UV LEDs has been analyzed and future prospects have been made as well. Firstly, this work provides a brief overview of the devices and analyzes why the packaging level reduces EQE and reliability in theory. Then, systematically reviews the recent advances in packaging technologies and deep UV micro‐LEDs. Finally, conclusions and outlooks are given as well. This review is of great significance for promoting the development of the packaging technologies for AlGaN‐based deep UV LEDs.

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High‐performance UV emitter grown on high‐crystalline‐quality AlGaN underlying layer

Cited by 50 publications

References 13 publications

Growth of low‐dislocation‐density AlGaN using Mg‐doped AlN underlying layer

Growth of low‐dislocation‐density AlGaN using Mg‐doped AlN underlying layer

Reduction in threshold current density of 355 nm UV laser diodes

Recent Advances in Packaging Technologies of AlGaN‐Based Deep Ultraviolet Light‐Emitting Diodes

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