Ultraviolet light-emitting diodes with polarization-doped p-type layer

Hu, Wenxiao; Qin, Ping; Song, Weidong; Zhang, Chongzhen; Wang, Rupeng; Zhao, Lingling; Xia, Chao; Yuan, Songyang; Yin, Yongsheng; Li, Shuti

doi:10.1016/j.spmi.2016.06.016

Cited by 11 publications

(4 citation statements)

References 10 publications

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“…Many studies have reported strategies of defect reduction via substrate or template, [18][19][20] methods of high carrier connement, and hole injection. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Low light extraction efficiency (LEE) is another challenge in achieving high efficiency for DUV LEDs. The LEE of the DUV LEDs has been improved by utilizing the ip-chip design, 36,37 a patterned sapphire substrate, 20,38 a patterned p-type layer, 39 and the nanowire structure.…”

Section: Introductionmentioning

confidence: 99%

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

et al. 2023

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Section: Introductionmentioning

confidence: 99%

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

et al. 2023

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“…Many studies proposed Mg-doped Al(In)GaN/Al(In)GaN superlattice structure to replace the electron blocking layer (EBL) to deal with low carrier confinement and hole injection issues. ,− This method can effectively increase the hole concentration and band offset of EBL to improve hole injection and electron confinement. In addition to EBL with an Al(In)GaN/Al(In)GaN superlattice structure, the use of the wide band gap interlayer, serrated p-AlGaN region, and step and linear , grading profiles of p-AlGaN was proposed to replace traditional p-AlGaN EBL. The p-AlGaN inserted layer with an aluminum percentage less than the last barrier and a thick Mg-doped last barrier increased hole injection efficiency, electron blocking efficiency, and hole concentration in the inserted layer.…”

Section: Introductionmentioning

confidence: 99%

AlGaN-Based Deep Ultraviolet Light-Emitting Diodes with Thermally Oxidized Al_xGa_2–xO₃ Sidewalls

et al. 2022

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AlGaN and GaN sidewalls were turned into Al x Ga 2– x O 3 and Ga 2 O 3 , respectively, by thermal oxidation to improve the optoelectrical characteristics of deep ultraviolet (DUV) light-emitting diodes (LEDs). The thermally oxidized Ga 2 O 3 is a single crystal with nanosized voids homogenously distributed inside the layer. Two oxidized Al x Ga 2– x O 3 layers were observed on the sidewall of the AlGaN layer in transmission electron microscopy images. The first oxidized Al x Ga 2– x O 3 layer is a single crystal, while the second oxidized Al x Ga 2–x O 3 layer is a single crystal with numerous nanosized voids inside. The composition of Al in the first oxidized Al x Ga 2– x O 3 layer is higher than that in the second one. The thermal oxidation at high temperature degrades the quality of the p-GaN layer and increases the forward voltage from 8.18 to 11.36 V. The thermally oxidized Al x Ga 2– x O 3 sidewall greatly enhances the light extraction efficiency of the lateral light of the DUV LEDs by combined mechanisms of holey structure, graded refractive index, high transparency, and tensile stress. Consequently, the light output power of the DUV LEDs increases from 0.69 to 0.88 mW by introducing a 420 nm thick Al x Ga 2– x O 3 sidewall oxidized at 900 °C, in which the enhancement of light output power can reach 27.5%.

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“…Researchers also designed the hole injection layers inserted between EBL and MQWs to effectively relieve the polarization-induced valence band bending [16]. Moreover, EBLs with graded composition [17], V-shaped structures [18], two-step tapered structures [19,20] as well as polarization doped layers [21] show favorable potentials for UV LEDs. However, most of these methods could still suffer from the Mg diffusion issue.…”

Section: Introductionmentioning

confidence: 99%

BAlN for III-nitride UV light-emitting diodes: undoped electron blocking layer

Gu¹,

Lu²,

Lin³

et al. 2021

J. Phys. D: Appl. Phys.

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The undoped BAlN electron-blocking layer (EBL) is investigated to replace the conventional AlGaN EBL in light-emitting diodes (LEDs). Numerical studies of the impact of variously doped EBLs on the output characteristics of LEDs demonstrate that the LED performance shows heavy dependence on the p-doping level in the case of the AlGaN EBL, while it shows less dependence on the p-doping level for the BAlN EBL. As a result, we propose an undoped BAlN EBL for LEDs to avoid the p-doping issues, which a major technical challenge in the AlGaN EBL. Without doping, the proposed BAlN EBL structure still possesses a superior capacity in blocking electrons and improving hole injection compared with the AlGaN EBL having high doping. Compared with the Al0.3Ga0.7N EBL with a doping concentration of 1 × 1020 cm−3, the undoped BAlN EBL LED still shows lower droop (only 5%), compatible internal quantum efficiency (2% enhancement), and optical output power (6% enhancement). This study provides a feasible route to addressing electron leakage and insufficient hole injection issues when designing ultraviolet LED structures.

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Ultraviolet light-emitting diodes with polarization-doped p-type layer

Cited by 11 publications

References 10 publications

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

AlGaN-Based Deep Ultraviolet Light-Emitting Diodes with Thermally Oxidized Al_xGa_2–xO₃ Sidewalls

BAlN for III-nitride UV light-emitting diodes: undoped electron blocking layer

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Ultraviolet light-emitting diodes with polarization-doped p-type layer

Cited by 11 publications

References 10 publications

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

The influences of AlGaN barrier epitaxy in multiple quantum wells on the optoelectrical properties of AlGaN-based deep ultra-violet light-emitting diodes

AlGaN-Based Deep Ultraviolet Light-Emitting Diodes with Thermally Oxidized AlxGa2–xO3 Sidewalls

BAlN for III-nitride UV light-emitting diodes: undoped electron blocking layer

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AlGaN-Based Deep Ultraviolet Light-Emitting Diodes with Thermally Oxidized Al_xGa_2–xO₃ Sidewalls