Continuous-wave lasing of AlGaN-based ultraviolet laser diode at 274.8 nm by current injection

Zhang, Ziyi; Kushimoto, Maki; Yoshikawa, Akira; Aoto, Koji; Schowalter, L. J.; Sasaoka, Chiaki; Amano, Hiroshi

doi:10.35848/1882-0786/ac6198

Cited by 34 publications

(16 citation statements)

References 32 publications

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“…This gap has a distinct correlation with threading dislocation densities typical for AlGaN alloys, which were shown in Figure 1 of the review reported in [ 24 ]. This correlation reveals a very critical effect of threading dislocation density (TDD) on the threshold current density of DUV-LDs, which was further confirmed by direct measurements reported in [ 25 , 28 , 29 , 30 ], see Figure 2 a (TDD for the lowest threshold current density shown in this figure was not reported in [ 25 ], but we estimated TDD in the range of ~10 6 –10 7 cm −2 ). The efforts aimed at TDD reduction, thus improving the threshold current density, will be discussed in more detail in Section 2 .…”

Section: Introductionsupporting

confidence: 90%

“…In the earlier demonstrations of injection-driven UVC LD [ 104 , 105 ], a 9 nm AlGaN SQW was used instead of the DQW. Because of asymmetric distribution of the AlGaN composition and cladding thicknesses in the LD structure, the DQWs are frequently shifted from the center of the WG towards n-AlGaN contact layer in order to increase the optical confinement factor (see Section 4.3 ) [ 25 , 26 ].…”

Section: Laser Structure Designmentioning

confidence: 99%

“…It should be noted that a minimum threshold current density of 3.7–4.3 kA/cm 2 [ 25 , 26 ] and room-temperature continuous-wave operation of lasers [ 26 ] have been achieved by using the structures grown on AlN substrates. This result agrees well with our consideration of the role of TDD for the threshold current control discussed in Section 2 .…”

Section: Laser Structure Designmentioning

confidence: 99%

“… Experimental threshold current densities of UV laser diodes fabricated on various substrates (symbols) vs. oscillation wavelength [ 24 , 25 , 26 ]. The grey line is an approximation for the minimum threshold current density drawn as a guide to the eye.…”

Section: Figurementioning

confidence: 99%

“…Figure 1 summarizes reported experimental threshold current densities (symbols) of UV laser diodes for different emission wavelengths. The data were obtained from [ 24 , 25 , 26 ]. Detailed description of the results by various research groups is given in [ 24 ].…”

Section: Introductionmentioning

confidence: 99%

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Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

Nikishin

Bernussi

Karpov³

2022

Nanomaterials

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The major issues confronting the performance of deep-UV (DUV) laser diodes (LDs) are reviewed along with the different approaches aimed at performance improvement. The impact of threading dislocations on the laser threshold current, limitations on heavy n- and p-doping in Al-rich AlGaN alloys, unavoidable electron leakage into the p-layers of (0001) LD structures, implementation of tunnel junctions, and non-uniform hole injection into multiple quantum wells in the active region are discussed. Special attention is paid to the current status of n- and p-type doping and threading dislocation density reduction, both being the factors largely determining the performance of DUV-LDs. It is shown that most of the above problems originate from intrinsic properties of the wide-bandgap AlGaN semiconductors, which emphasizes their fundamental role in the limitation of deep-UV LD performance. Among various remedies, novel promising technological and design approaches, such as high-temperature face-to-face annealing and distributed polarization doping, are discussed. Whenever possible, we provided a comparison between the growth capabilities of MOVPE and MBE techniques to fabricate DUV-LD structures.

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Section: Introductionsupporting

confidence: 90%

Section: Laser Structure Designmentioning

confidence: 99%

Section: Laser Structure Designmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

Nikishin

Bernussi

Karpov³

2022

Nanomaterials

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Lasing Threshold Reduction of AlGaN‐Based Ultraviolet‐C Laser Diodes Using Strain Relaxed Lower Cladding Layer

Ren,

Liu,

Guo

et al. 2024

Physica Status Solidi (a)

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The dependence of the performance of ultraviolet‐C (UV‐C) laser diodes on the strain relaxation of lower cladding layer (LCL) is numerically investigated. As the strain relaxation increases from 0% to 100%, the threshold current density decreases from 25 to 12.7 kA cm−2, and the slope efficiency increases from 0.039 to 0.087 W A−1, thanks to an increase in internal quantum efficiency (IQE). The improvement of IQE is mainly due to the enhanced hole injection resulting from the increased hole concentration in the distributed polarization doping layers and the reduced hole blocking barrier height of the upper waveguide layer with increasing the strain relaxation. Additionally, the effective screening of the polarization field within the quantum well ameliorates the quantum‐confined Stark effect, further improving the IQE. Our study reveals that strain relaxed LCL is imperative to achieve low‐threshold UV‐C laser diodes.

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Effect of Wet Etching on AlGaN‐Based Ultraviolet‐B Laser Diodes Grown on Wet‐Etched Periodic AlN Nanopillars

Imoto,

Hasegawa,

Yabutani

et al. 2024

Physica Status Solidi (a)

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The effect of wet etching on the characteristics of ultraviolet‐B (UV‐B) lasers fabricated on AlGaN templates grown as crystals or wet‐etched AlN nanopillars is compared in detail. Specifically, a tetramethylammonium hydroxide (TMAH) solution is used to form templates with AlN nanopillars of different diameters, followed by determining the dependence of the dislocation density in AlGaN crystals grown on the templates, the threshold power density (Pth) of an optically pumped UV‐B laser, and the threshold current density (Jth) of a UV‐B laser diode (LD) on the extent of etching. It is observed that the pillar diameter decreases almost linearly as the etching time with the TMAH solution increases. The dislocation density of AlGaN crystals grown on AlGaN templates is almost independent of the etching time. Meanwhile, Pth of the optically pumped UV‐B laser is almost halved upon etching with TMAH. Finally, the Jth of the UV‐B LD tends to decrease by 10%–20% upon etching. The optical gain is estimated by optical excitation; wet etching of AlN nanopillars with TMAH solution results in a larger optical gain at the same excitation intensity, indicating that nonradiative recombination centers, such as point defects, are reduced.

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Continuous-wave lasing of AlGaN-based ultraviolet laser diode at 274.8 nm by current injection

Cited by 34 publications

References 32 publications

Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

Towards Efficient Electrically-Driven Deep UVC Lasing: Challenges and Opportunities

Lasing Threshold Reduction of AlGaN‐Based Ultraviolet‐C Laser Diodes Using Strain Relaxed Lower Cladding Layer

Effect of Wet Etching on AlGaN‐Based Ultraviolet‐B Laser Diodes Grown on Wet‐Etched Periodic AlN Nanopillars

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