Modulating the Layer Resistivity by Band-Engineering to Improve the Current Spreading for DUV LEDs

Chu, Chunshuang; Chen, Qian; Tian, Kangkai; Che, Jiamang; Shao, Hua; Kou, Jianquan; Zhang, Yonghui; Chen, Chang; Zhang, Zihui; Dai, Jiangnan

doi:10.1109/lpt.2019.2920527

Cited by 11 publications

(4 citation statements)

References 33 publications

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“…In 2018 Che et al designed a p -AlGaN/ n -AlGaN/ p -AlGaN structured current spreading layer in the p -type hole injection layer 174 . In 2019 Chun et al improved the current spreading of DUV LEDs by modulating the resistivity in the n -AlGaN layer 175 . Zhang et al proposed a honeycomb hole-shaped structure of an electrode to improve the current spreading for 280-nm DUV LED 176 .…”

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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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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“…However, the n-side could play a role in the design of DUV LEDs [118]. A recent study proves that band engineering in the n-AlGaN region can reduce the current crowding effect by adding an n-type barrier layer [119]. In that work, the reference structure (LED A) has a 1.5 µm thick Si-doped n-Al 0.57 Ga 0.43 N layer while an additional 10 nm-thick n-Al 0.67 Ga 0.23 N insert layer was added between the thick n-Al 0.57 Ga 0.43 N layer and the active region in the proposed LED B, as illustrated in figure 16(a).…”

Section: Band Engineering Of N-and P-type Injection Layermentioning

confidence: 99%

“…Early studies have demonstrated that a B x Al 1−x N/Al y Ga 1−y N heterostructure could possibly create a large potential barrier for electron blocking while also offering minimum valence band offsets for hole injection as a result of their unique band offset characteristics-a nearly zero valence band offset in B x Al 1−x N/Al y Ga 1−y N heterostructures [142][143][144][145][146]. In addition to these promising strategies, proper design of band structures in the LQB and p-AlGaN hole injection layer, which n-and p-type injection layer design Changed Al-composition of p-region An electric-field reservoir [115] PNP-AlGaN structured current spreading layers [137] Graded p-type layer Serrated p-type layer [117] Segmentally graded p-type layer [138] Multilayers in p-region SL p-contact layer [139] Insertion layers in n-region HBL [119] TJ implementation Metal [140] Wide band-gap materials [141] Narrow band-gap materials [121,123,124] Sections Methods Structures Ref.…”

Section: Conclusion and Prospectsmentioning

confidence: 99%

Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: a review

Ren

Liu

et al. 2019

J. Phys. D: Appl. Phys.

109

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III-nitride deep ultraviolet (DUV) light-emitting diodes (LEDs) have been identified as promising candidates for energy-efficient, environment-friendly and robust UV lighting sources with potential applications in water/air purification, sterilization, and bio-sensing. However, the performance of state-of-art DUV LEDs is far from satisfactory for commercialization due to their low internal quantum efficiency, large current leakage and efficiency droop at high current injection, etc. Extensive efforts have been devoted to properly designing the band structures of such luminescent devices to enhance their output power. In this review, we summarize the recent progress of various energy band designs and of the engineering of DUV LEDs, with particular attention paid to the various approaches in band engineering of electron-blocking layers, quantum wells, quantum barriers and the implementation of many novel structures such as tunnel junctions and ultrathin quantum heterostructures utilized to enhance their efficiency. These inspirational approaches pave the way towards the next generation of greener and more efficient UV sources suitable for practical applications.

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“…All of these efficiencies are responsible for the low EQE of AlGaN UV LEDs [9]. This issue has been addressed by applying a p-type AlGaN electron blocking layer (EBL) to prevent the electron overflow, which has resulted in increased external quantum efficiency (EQE) and optical power output [2,10]. Other studies have applied p-type AlxGa1−xN layers with stepgraded values of x as EBLs in GaN-based LEDs.…”

Section: Introductionmentioning

confidence: 99%

Improved Performance of GaN-Based Ultraviolet LEDs With Electron Blocking Layers Composed of Double-Peak p-Type Al_xGa_1−xN/GaN Superlattice Layers

2021

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Past studies have demonstrated the positive impact of step-graded p-type AlxGa1−xN/GaN superlattice (SL) electron blocking layer (EBL) structures on the efficiency performance of ultraviolet (UV) GaN-based light-emitting diodes (LEDs). However, the optimal Al-grading structure of these SL EBLs remains unclear owing to a lack of systematic investigation. The present work addresses this issue by applying EBL composed of alternating half-peak, single-peak, and double-peak p-type AlxGa1−xN/GaN SL structures with varying values of x ranging from 0.05 to 0.15 in 0.05 step increments. Simulation analysis is employed to obtain the internal quantum efficiency (IQE), energy band diagrams, polarization compensation factor, hole concentration, and electron concentration of GaN-based UV LEDs with three different SL-EBL structures. The results obtained at an injection current of 200 mA demonstrate that UV LEDs with double-peak SL-EBL structures provide the maximum IQE, which is ~38% greater than that of devices employing the conventional EBL in simulation experiment. This SL-EBL is demonstrated to improve the hole injection and electron overflow performance of GaN-based UV LEDs owing to the polarization charge and lattice mismatch at the p-AlxGa1−xN/GaN interfaces. The reduced Al composition on the p-GaN side reduces the potential barrier of hole injection. Moreover, the predicted increase in the IQE of GaN-based UV LEDs with the optimal SL-EBL is verified experimentally.

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Modulating the Layer Resistivity by Band-Engineering to Improve the Current Spreading for DUV LEDs

Cited by 11 publications

References 33 publications

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

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

Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: a review

Improved Performance of GaN-Based Ultraviolet LEDs With Electron Blocking Layers Composed of Double-Peak p-Type Al_xGa_1−xN/GaN Superlattice Layers

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Modulating the Layer Resistivity by Band-Engineering to Improve the Current Spreading for DUV LEDs

Cited by 11 publications

References 33 publications

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

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

Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: a review

Improved Performance of GaN-Based Ultraviolet LEDs With Electron Blocking Layers Composed of Double-Peak p-Type Al x Ga1−x N/GaN Superlattice Layers

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Improved Performance of GaN-Based Ultraviolet LEDs With Electron Blocking Layers Composed of Double-Peak p-Type Al_xGa_1−xN/GaN Superlattice Layers