Increasing the hole energy by grading the alloy composition of the p-type electron blocking layer for very high-performance deep ultraviolet light-emitting diodes

Zhang, Zi Hui; Kou, Jianquan; Chen, Sung Wen Huang; Shao, Hua; Che, Jiamang; Chu, Chunshuang; Tian, Kangkai; Zhang, Yonghui; Bi, Wengang; Kuo, Hao‐Chung

doi:10.1364/prj.7.0000b1

Cited by 59 publications

(30 citation statements)

References 26 publications

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“…We also show the calculated EL spectra for Devices A and B in the inset for Fig. 3(b), and the similar phenomena are obtained, such that the parasitic emission of 335 nm is absent for Device B [32]. Note, although we have set the same growth recipe to keep the identical conditions, the measured peak emission wavelength for Device B is still shorter by ∼10 nm than that for Device A, and we attribute this to the higher Al composition in the quantum wells which is estimated to be 50%.…”

Section: Resultssupporting

confidence: 76%

On the Impact of Electron Leakage on the Efficiency Droop for AlGaN Based Deep Ultraviolet Light Emitting Diodes

et al. 2020

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In this work, we have investigated the origin of efficiency droop for AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs). We find that the efficiency droop is likely to be caused by the electron leakage for DUV LEDs studied in this work. The electron leakage arises from the unbalanced electron and hole injection efficiencies. The correlation between the efficiency droop and the electron leakage can be numerically calculated by manipulating the conduction band barrier height of the p-AlGaN electron blocking layer (p-EBL) for the proposed DUV LEDs. For the purpose of demonstrating that the efficiency droop for DUV LEDs can be experimentally decreased by reducing the electron leakage, a p +-GaN/In 0.15 Ga 0.85 N/n +-GaN tunnel junction on DUV LED is grown by using metal organic chemical vapor deposition (MOCVD) technology. The tunnel junction helps to enhance the hole injection, thus decreasing the electron leakage and the efficiency droop. Moreover, the parasitic emission in the p-type hole injection layer is no longer observed thanks to the decreased electron leakage level.

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Section: Resultssupporting

confidence: 76%

On the Impact of Electron Leakage on the Efficiency Droop for AlGaN Based Deep Ultraviolet Light Emitting Diodes

et al. 2020

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“…Liu et al proposed an AlGaN SLs with varying barriers as the EBL of DUV LED, thereby causing the efficiency droop decreased from 80.8% to 28.8% 165 . In 2017 and 2018, Zhang et al modified the barrier height for EBL by utilizing p -Al 0.60 Ga 0.40 N (L2)/Al 0.50 Ga 0.50 N/ p -Al 0.60 Ga 0.40 N (L1) EBL and grading the alloy composition respectively, to guarantees a smooth hole injection into the active region 166 , 167 . In 2019, Lang et al adopted an Al-composition and thickness-graded multiple quantum barriers structure as polarization-modulated EBL to enhance the carrier transport in DUV LED 168 .…”

Section: Manipulation Of Polarization Fieldsmentioning

confidence: 99%

Multiple fields manipulation on nitride material structures in ultraviolet light-emitting diodes

Gao

Cai

et al. 2021

Light Sci Appl

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As demonstrated during the COVID-19 pandemic, advanced deep ultraviolet (DUV) light sources (200–280 nm), such as AlGaN-based light-emitting diodes (LEDs) show excellence in preventing virus transmission, which further reveals their wide applications from biological, environmental, industrial to medical. However, the relatively low external quantum efficiencies (mostly lower than 10%) strongly restrict their wider or even potential applications, which have been known related to the intrinsic properties of high Al-content AlGaN semiconductor materials and especially their quantum structures. Here, we review recent progress in the development of novel concepts and techniques in AlGaN-based LEDs and summarize the multiple physical fields as a toolkit for effectively controlling and tailoring the crucial properties of nitride quantum structures. In addition, we describe the key challenges for further increasing the efficiency of DUV LEDs and provide an outlook for future developments.

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“…These technical challenges severely hinder the progress to fully replace the conventional mercury-based UV light sources. Furthermore, the quantum-confined stark effect and electron leakage are pronounced in AlGaN quantum wells [17], [18]. Insufficient hole concentration and feeble capability confining electrons significantly reduce the efficiency at high current injection levels.…”

Section: Introductionmentioning

confidence: 99%

Greatly Enhanced Wall-Plug Efficiency of N-polar AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

Tao

Fan

et al. 2021

IEEE Photonics J.

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In this work, we numerically investigate the N-polar AlGaN-based deep ultraviolet light-emitting diodes (DUV LEDs) over the Ga-polar DUV LEDs. The light output power has increased from 7.1 mW of Ga-polar DUV LED to 18.8 mW of N-polar DUV LED at 60 mA, and the wall-plug efficiency (WPE) of N-polar DUV LED is boosted by 104% at 60 mA with the same structure of Ga-polar conventional DUV LED. Furthermore, the higher operation voltage of N-polar DUV LED induced by the large energy difference between the p-type interlayer and the p-GaN hole supplier is noted. To reduce the operation voltage of N-polar DUV LED, the structure with a staircase-like p-type interlayer is proposed. The incorporation of staircase-like aluminum composition p-type interlayer mitigates the large potential barrier for holes injection, and the operation voltage is comparable to the Ga-polar DUV LED. The reduced operation voltage further promotes the WPE of N-polar DUV LEDs. Thus, combined with the promoted electron blocking ability and the mitigated potential barrier for holes of N-polar DUV LED, the greatly enhanced WPE is as high as 4.9% at 60 mA, which is 2.88 times higher than the Ga-polar DUV LED.

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Increasing the hole energy by grading the alloy composition of the p-type electron blocking layer for very high-performance deep ultraviolet light-emitting diodes

Cited by 59 publications

References 26 publications

On the Impact of Electron Leakage on the Efficiency Droop for AlGaN Based Deep Ultraviolet Light Emitting Diodes

On the Impact of Electron Leakage on the Efficiency Droop for AlGaN Based Deep Ultraviolet Light Emitting Diodes

Multiple fields manipulation on nitride material structures in ultraviolet light-emitting diodes

Greatly Enhanced Wall-Plug Efficiency of N-polar AlGaN-Based Deep Ultraviolet Light-Emitting Diodes

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