Demonstration of ultraviolet-B AlGaN-based laser diode operation with a peak light output power of 150 mW by improving injection efficiency through polarization charge modulation

Kondo, Ryosuke; Yabutani, Ayumu; Omori, Tomoya; Yamada, Kazuki; Matsubara, Eri; Hasegawa, Ryota; Nishibayashi, Toma; Iwayama, Sho; Takeuchi, Tetsuya; Kamiyama, Satoshi; Miyake, Hideto; Sato, Kosuke

doi:10.1063/5.0135033

Cited by 11 publications

(3 citation statements)

References 27 publications

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“…Moreover, the dependence of η i changes on the difference in polarization between the p ‐side guide and electron‐blocking layers has been reported in polarization doping. [ 33 ] The presence of V‐shaped pits leads to a greater spatial variation in AlN molar fraction, which could cause changes in η i . Although the mechanism of the increase in η i requires further investigation, we believe that it is extremely important to reduce the V‐shaped pits and dislocation densities to realize a high‐performance UV‐B LD.…”

Section: Methodsmentioning

confidence: 99%

Performance of Ultraviolet‐B Laser Diodes on AlGaN Templates Prepared Using Different Fabrication Methods

Matsubara

Omori

Hasegawa

et al. 2023

Physica Status Solidi (a)

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Herein, the differences in the characteristics of ultraviolet‐B (UV‐B) laser diodes (LDs) are investigated and fabricated on AlGaN templates prepared using two types of fabrication methods: 1) spontaneous nucleation in which AlGaN is grown 3D from spontaneously generated AlN crystal nuclei and 2) AlN nanopillar in which AlGaN is grown on AlN nanopillars. The LD formed on the AlGaN fabricated using the AlN nanopillar method of slope efficiency and maximum peak light output power is improved four and six times, respectively, which are significantly better compared with the spontaneous nucleation method. The analysis also confirms the differences in injection efficiency and internal loss in the semiconductor crystal. Furthermore, detailed analysis of the current–voltage characteristics shows that the AlN nanopillar method has lower reverse leakage current and n‐value than the spontaneous nucleation method. Comparison of these differences with crystallographic properties suggests that these differences in device properties are manifested by differences in V‐shaped pits and dislocation density. The reduction of dislocations and V‐shaped pit density in an AlGaN template is important to realize high‐performance UV‐B LDs, and the AlN nanopillar method is found to be useful for the fabrication of a suitable AlGaN template.

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Section: Methodsmentioning

confidence: 99%

Performance of Ultraviolet‐B Laser Diodes on AlGaN Templates Prepared Using Different Fabrication Methods

Matsubara

Omori

Hasegawa

et al. 2023

Physica Status Solidi (a)

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“…These AlGaN templates are used as an underlying layer for UV-B LDs. [20][21][22] Previously, it has been reported that AlOOH, Al(OH) 3 , and Al 2 O 3 are formed by reaction with water for AlN powders and polycrystalline substrates. [23][24][25][26] In the report, 19) an alteration layer is formed by heating and pressurizing water, and the alteration layer is identified as AlOOH using the X-ray diffraction method.…”

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confidence: 99%

Exfoliation mechanism of AlGaN-based thin films using heated-pressurized water

Yamada,

Matsubara,

Kondo

et al. 2023

Appl. Phys. Express

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This study investigated the crystallographic plane dependence of the reaction of AlN and AlGaN using heated-pressurized water under saturated vapor pressure. The results show that the reaction strongly depends on the crystallographic orientation plane, with no reaction in the +c-plane, the formation of an AlOOH-altered layer in the −c-plane, and etching in the a- and m-planes. These results suggest that the exfoliation mechanism of AlGaN grown on periodically formed AlN nanopillars on sapphire substrates using heated-pressurized water involves etching of a- and m-plane crystals, demonstrating that the proposed method is highly reproducible and versatile for large-diameter wafer exfoliation.

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“…However, most of the reported light output from a single LED or LD chip is only a few hundred mW at most. 21,22) Therefore, the primary challenge in future studies will revolve around increasing the light output of these devices. The light output of a single LED or LD chip depends on the efficiency of each device and the input current.…”

mentioning

confidence: 99%

Fabrication of vertical AlGaN-based ultraviolet-B laser diodes using a laser lift-off method

Nishibayashi,

Kondo,

Matsubara

et al. 2023

Appl. Phys. Express

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Vertical AlGaN-based UV-B laser diodes were fabricated by a laser lift-off method to exfoliate sapphire substrates. These devices were processed on 1-cm2 square wafers with a polycrystalline sintered AlN substrate as a structural support for the exfoliated device. Following electrode formation and other necessary processing steps, mirrors were formed through cleavage. Subsequently, the performance of the device was evaluated by injecting a pulsed current at room temperature. Results revealed distinct characteristics, including a sharply emission at 298.1 nm, a well-defined threshold current, strong transverse-electric polarization characteristic, and a laser-specific spot-like far-field pattern, confirming the oscillation of the vertical laser diode.

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Demonstration of ultraviolet-B AlGaN-based laser diode operation with a peak light output power of 150 mW by improving injection efficiency through polarization charge modulation

Cited by 11 publications

References 27 publications

Performance of Ultraviolet‐B Laser Diodes on AlGaN Templates Prepared Using Different Fabrication Methods

Performance of Ultraviolet‐B Laser Diodes on AlGaN Templates Prepared Using Different Fabrication Methods

Exfoliation mechanism of AlGaN-based thin films using heated-pressurized water

Fabrication of vertical AlGaN-based ultraviolet-B laser diodes using a laser lift-off method

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