Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design

Yifei Dong; Dongxu Zhu; Kai Guo; Kaixin Li; Xiaona Zhang; Chong Wang; Chunshuang Chu; Kangkai Tian; Haoyan Liu; Yonghui Zhang; Naixin Liu; Zi-Hui Zhang; Jianchang Yan

doi:10.1088/1674-4926/26030027

J. Semicond. > In Press

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Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design

Yifei Dong^{1, 2}, Dongxu Zhu^{1, 2}, Kai Guo⁷, Kaixin Li⁷, Xiaona Zhang⁷, Chong Wang^{1, 2, 7}, Chunshuang Chu³, Kangkai Tian³, Haoyan Liu^{1, 2}, Yonghui Zhang^{1, 2,}, Naixin Liu^{5, 7,}, Zi-Hui Zhang^{1, 3, 4} and Jianchang Yan^{5, 6}

+ Author Affiliations

1. State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electronics and Information Engineering, University Hebei of Technology, Tianjin 300401, China
2. Key Laboratory of Electronic Materials and Devices of Tianjin, 5340 Xiping Road, Beichen District, Tianjin 300401, China
3. School of Integrated Circuits, Guangdong University of Technology, 100 Waihuan West Road, Fanyu District, Guangzhou City, Guangdong Province, 510006, China
4. Tianjin San'an Optoelectronics Co., Ltd, Tianjin 300450, China
5. The Research and Development Center for Wide Bandgap Semiconductors Institute of Semiconductors Chinese Academy of Sciences, Beijing 100083, China
6. School of Integrated Circuit Science and Engineering, Beihang University
7. Shanxi Semiconductor Deep Ultraviolet Technology Innovation Center, Advanced Ultraviolet Optoelectronics Company Ltd, and Shanxi Zhongke Lu'an Semiconductor Technology Research Institute Co., Ltd, Changzhi, Shanxi 046000, China

Author Bio:

Yifei Dong got his bachelor's degree in 2024 from Hebei University of Technology. Now he is a master's student at Hebei University of Technology under the supervision of Prof. Yonghui Zhang. His research focuses on the fabrication of AlGaN-based deep-ultraviolet light-emitting diodes.

Yonghui Zhang received his doctoral degree from the Institute of Semiconductors in 2015. He is currently a Professor at Hebei University of Technology, Tianjin, China. His current research interests include simulation, design, and fabrication of third-generation semiconductor optoelectronic devices.

Naixin Liu received his doctoral degree from the Institute of Semiconductors in 2009. He is currently an Associate Professor with the Institute of Semiconductors, Chinese Academy of Sciences, Beijing, China. His current research interests include epitaxial growth of wide-bandgap nitride semiconductor materials and light-emitting devices.

Corresponding author: Yonghui Zhang, zhangyh@hebut.edu.cn; Naixin Liu, nxliu@semi.ac.cn

DOI: 10.1088/1674-4926/26030027CSTR: 32376.14.1674-4926.26030027

Abstract: Electrode design is critical for the performance and reliability of flip-chip AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs). We propose a semi-surround n-electrode design to achieve better current spreading for a relatively small DUV LED with a size of 8×15 mil². It is found that an optimal semi-surround n-electrode can reduce the operating voltage and increase the chip reliability due to the larger ohmic contact area. Moreover, the semi-surround n-electrode introduces multiple current injection paths, which causes the improvement of the current spreading in both the directions parallel (X) and perpendicular (Y) to the electrode fingers. However, an excessively long semi-surround n-electrode will decrease the light output power because of the severely reduced active region area. Furthermore, experiments and simulations reveal that the semi-surround n-electrode can improve the current spreading in the Y direction at high injection current. Meanwhile, it is also found that a short semi-surround n-electrode causes deteriorated current spreading in the X direction due to the unbalanced resistance between n-electrode and p-electrode. Our work highlights the importance of two-dimensional current management in electrode design and provides a practical strategy for developing high-performance and reliable DUV LEDs with a relatively small chip size.

Keywords: DUV LEDs, current spreading, semi-surround n-electrode.

References

[1]	Lu Y, Guo Y N, Liu Z Y, et al. Monolithic integration of deep ultraviolet and visible light-emitting diodes for radiative sterilization application. Appl Phys Lett, 2024, 124(11): 111102 doi: 10.1063/5.0180411
[2]	Mohaghegh Montazeri M, Hejazi S A, Taghipour F. Ultraviolet light-emitting diode (UV-LED) water disinfection photoreactors: A review. J Environ Manag, 2025, 386: 125678 doi: 10.1016/j.jenvman.2025.125678
[3]	Saito Y, Miyazaki A, Boyama M, et al. Improvement of the reliability of AlGaN-based UV-C LEDs and application of water purification. Gallium Nitride Materials and Devices XXI, 2026: 42
[4]	Wang R, Yu H B, Memon M H, et al. Integrated deep-ultraviolet micro-LED array with ultralow contact resistance and ultrahigh bandwidth for intermixed solar-blind optical wireless communication. IEEE Electron Device Lett, 2024, 45(12): 2479 doi: 10.1109/LED.2024.3472009
[5]	Memon M H, Yu H B, Jia H F, et al. Micro-trench deep-ultraviolet LEDs with boosted efficiency for high-speed solar-blind optical communication. J Light Technol, 2025, 43(5): 2248 doi: 10.1109/JLT.2024.3486102
[6]	Gao Y P, Tian W T, Qi Y, et al. Interfacial polarization charge engineering with co-designed LQB and EBL for enhanced EQE of AlGaN DUV LEDs. Semicond Sci Technol, 2025, 40(1): 015021 doi: 10.1088/1361-6641/ad98b7
[7]	Hao L B, Guo Y N, Su D L, et al. Effects of the substrate thickness and chip area on the light extraction efficiency of chip-scale liquid cup encapsulated AlGaN-based deep-ultraviolet light-emitting diodes. Opt Express, 2025, 33(23): 48299 doi: 10.1364/OE.579872
[8]	Chen Y F, Lv Q J, Yang T P, et al. Design and optimization of epitaxial and chip structures in AlGaN-based deep-ultraviolet LEDs: Toward enhanced efficiency and reliability. ACS Photonics, 2026, 13(4): 878 doi: 10.1021/acsphotonics.5c02187
[9]	Liang S H, Sun W H. Recent advances in packaging technologies of AlGaN-based deep ultraviolet light-emitting diodes. Adv Mater Technol, 2022, 7(8): 2101502 doi: 10.1002/admt.202101502
[10]	Liu Z Q, Jia T, Xu X Y, et al. Research progress of AlGaN-based DUV μLED (invited). Infrared Laser Eng, 2023, 52(8): 20230390 doi: 10.3788/IRLA20230390
[11]	Xiao S D, Yu H B, Memon M H, et al. In-depth investigation of deep ultraviolet MicroLED geometry for enhanced performance. IEEE Electron Device Lett, 2023, 44(9): 1520 doi: 10.1109/LED.2023.3294819
[12]	Chen Y F, Lv Q J, Liu J, et al. Mitigating current crowding for enhanced reliability of AlGaN-based deep-ultraviolet LEDs through triangular island-shaped p-electrode design. Opt Laser Technol, 2025, 181: 112026 doi: 10.1016/j.optlastec.2024.112026
[13]	Zhang S, Wu F, Wang S, et al. Enhanced wall-plug efficiency in AlGaN-based deep-ultraviolet LED via a novel honeycomb hole-shaped structure. IEEE Trans Electron Devices, 2019, 66(7): 2997 doi: 10.1109/TED.2019.2913962
[14]	Chen Q, Dai J N, Li X H, et al. Enhanced optical performance of AlGaN-based deep ultraviolet light-emitting diodes by electrode patterns design. IEEE Electron Device Lett, 2019, 40(12): 1925 doi: 10.1109/LED.2019.2948952
[15]	Che J M, Shao H, Kou J Q, et al. Improving the current spreading by locally modulating the doping type in the n-AlGaN layer for AlGaN-based deep ultraviolet light-emitting diodes. Nanoscale Res Lett, 2019, 14(1): 268 doi: 10.1186/s11671-019-3078-8
[16]	Hao L B, Wang L, Guo Y N, et al. Enhancing the performance for high-power AlGaN-based deep ultraviolet light-emitting diodes using self-assembled chip-scale inclined sidewall. IEEE Electron Device Lett, 2025, 46(3): 377 doi: 10.1109/LED.2025.3531443
[17]	Guo X, Schubert E F. Current crowding and optical saturation effects in GaInN/GaN light-emitting diodes grown on insulating substrates. Appl Phys Lett, 2001, 78(21): 3337 doi: 10.1063/1.1372359
[18]	Cho J, Schubert E F, Kim J K. Efficiency droop in light-emitting diodes: Challenges and countermeasures. Laser Photonics Rev, 2013, 7(3): 408 doi: 10.1002/lpor.201200025

Fig. 1. (Color online) Schematic structure of the DUV LEDs (a) without and with semi-surround n-electrode and (b) micrograph images of three different LED.

DownLoad: Full-Size Img PowerPoint

Fig. 2. (Color online) Optical and electric properties results for LED A, LED B, and LED C. (a) Linear-scale I−V characteristics of DUV LEDs, and logarithmic-scale I−V curves are shown in the inserted image. (b) LOP and WPE as a function of the injection current. (c) EL spectra for different DUV LEDs.

DownLoad: Full-Size Img PowerPoint

Fig. 3. (Color online) The emission graphs of three DUV LEDs at injection current of (a) 40 mA and (b)150 mA. The simplified equivalent circuit paths of DUV LEDs (c1) without and (c2) with a semi-surround n-electrode.

DownLoad: Full-Size Img PowerPoint

Fig. 4. (Color online) Schematic diagrams of current paths in AlGaN-based DUV LEDs (a1) without and (a2) with a semi-surround n-electrode, and (a3) the simplified equivalent circuit. (b) Simulation results of the current density distribution for the three DUV LEDs.

DownLoad: Full-Size Img PowerPoint

Fig. 5. (Color online) Normalized LOP curves, with aging time at injection currents of 40 and 100 mA.

DownLoad: Full-Size Img PowerPoint

[1]	Lu Y, Guo Y N, Liu Z Y, et al. Monolithic integration of deep ultraviolet and visible light-emitting diodes for radiative sterilization application. Appl Phys Lett, 2024, 124(11): 111102 doi: 10.1063/5.0180411
[2]	Mohaghegh Montazeri M, Hejazi S A, Taghipour F. Ultraviolet light-emitting diode (UV-LED) water disinfection photoreactors: A review. J Environ Manag, 2025, 386: 125678 doi: 10.1016/j.jenvman.2025.125678
[3]	Saito Y, Miyazaki A, Boyama M, et al. Improvement of the reliability of AlGaN-based UV-C LEDs and application of water purification. Gallium Nitride Materials and Devices XXI, 2026: 42
[4]	Wang R, Yu H B, Memon M H, et al. Integrated deep-ultraviolet micro-LED array with ultralow contact resistance and ultrahigh bandwidth for intermixed solar-blind optical wireless communication. IEEE Electron Device Lett, 2024, 45(12): 2479 doi: 10.1109/LED.2024.3472009
[5]	Memon M H, Yu H B, Jia H F, et al. Micro-trench deep-ultraviolet LEDs with boosted efficiency for high-speed solar-blind optical communication. J Light Technol, 2025, 43(5): 2248 doi: 10.1109/JLT.2024.3486102
[6]	Gao Y P, Tian W T, Qi Y, et al. Interfacial polarization charge engineering with co-designed LQB and EBL for enhanced EQE of AlGaN DUV LEDs. Semicond Sci Technol, 2025, 40(1): 015021 doi: 10.1088/1361-6641/ad98b7
[7]	Hao L B, Guo Y N, Su D L, et al. Effects of the substrate thickness and chip area on the light extraction efficiency of chip-scale liquid cup encapsulated AlGaN-based deep-ultraviolet light-emitting diodes. Opt Express, 2025, 33(23): 48299 doi: 10.1364/OE.579872
[8]	Chen Y F, Lv Q J, Yang T P, et al. Design and optimization of epitaxial and chip structures in AlGaN-based deep-ultraviolet LEDs: Toward enhanced efficiency and reliability. ACS Photonics, 2026, 13(4): 878 doi: 10.1021/acsphotonics.5c02187
[9]	Liang S H, Sun W H. Recent advances in packaging technologies of AlGaN-based deep ultraviolet light-emitting diodes. Adv Mater Technol, 2022, 7(8): 2101502 doi: 10.1002/admt.202101502
[10]	Liu Z Q, Jia T, Xu X Y, et al. Research progress of AlGaN-based DUV μLED (invited). Infrared Laser Eng, 2023, 52(8): 20230390 doi: 10.3788/IRLA20230390
[11]	Xiao S D, Yu H B, Memon M H, et al. In-depth investigation of deep ultraviolet MicroLED geometry for enhanced performance. IEEE Electron Device Lett, 2023, 44(9): 1520 doi: 10.1109/LED.2023.3294819
[12]	Chen Y F, Lv Q J, Liu J, et al. Mitigating current crowding for enhanced reliability of AlGaN-based deep-ultraviolet LEDs through triangular island-shaped p-electrode design. Opt Laser Technol, 2025, 181: 112026 doi: 10.1016/j.optlastec.2024.112026
[13]	Zhang S, Wu F, Wang S, et al. Enhanced wall-plug efficiency in AlGaN-based deep-ultraviolet LED via a novel honeycomb hole-shaped structure. IEEE Trans Electron Devices, 2019, 66(7): 2997 doi: 10.1109/TED.2019.2913962
[14]	Chen Q, Dai J N, Li X H, et al. Enhanced optical performance of AlGaN-based deep ultraviolet light-emitting diodes by electrode patterns design. IEEE Electron Device Lett, 2019, 40(12): 1925 doi: 10.1109/LED.2019.2948952
[15]	Che J M, Shao H, Kou J Q, et al. Improving the current spreading by locally modulating the doping type in the n-AlGaN layer for AlGaN-based deep ultraviolet light-emitting diodes. Nanoscale Res Lett, 2019, 14(1): 268 doi: 10.1186/s11671-019-3078-8
[16]	Hao L B, Wang L, Guo Y N, et al. Enhancing the performance for high-power AlGaN-based deep ultraviolet light-emitting diodes using self-assembled chip-scale inclined sidewall. IEEE Electron Device Lett, 2025, 46(3): 377 doi: 10.1109/LED.2025.3531443
[17]	Guo X, Schubert E F. Current crowding and optical saturation effects in GaInN/GaN light-emitting diodes grown on insulating substrates. Appl Phys Lett, 2001, 78(21): 3337 doi: 10.1063/1.1372359
[18]	Cho J, Schubert E F, Kim J K. Efficiency droop in light-emitting diodes: Challenges and countermeasures. Laser Photonics Rev, 2013, 7(3): 408 doi: 10.1002/lpor.201200025

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History

Received: 17 March 2026 Revised: 12 May 2026 Online: Uncorrected proof: 03 June 2026

Article Navigation > Journal of Semiconductors > 2026 > Uncorrected proof

Yifei Dong, Dongxu Zhu, Kai Guo, Kaixin Li, Xiaona Zhang, Chong Wang, Chunshuang Chu, Kangkai Tian, Haoyan Liu, Yonghui Zhang, Naixin Liu, Zi-Hui Zhang, Jianchang Yan. Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design[J]. Journal of Semiconductors, 2026, In Press. doi: 10.1088/1674-4926/26030027 ****Y F Dong, D X Zhu, K Guo, K X Li, X N Zhang, C Wang, C S Chu, K K Tian, H Y Liu, Y H Zhang, N X Liu, Z H Zhang, and J C Yan, Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/26030027

Citation:

Y F Dong, D X Zhu, K Guo, K X Li, X N Zhang, C Wang, C S Chu, K K Tian, H Y Liu, Y H Zhang, N X Liu, Z H Zhang, and J C Yan, Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design[J]. J. Semicond., 2026, accepted doi: 10.1088/1674-4926/26030027

Citation:

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Enhancing the performance of flip-chip deep ultraviolet light-emitting diodes with a small chip size via a semi-surrounded n-electrode design

DOI: 10.1088/1674-4926/26030027

CSTR: 32376.14.1674-4926.26030027

Yifei Dong^{1, 2},
Dongxu Zhu^{1, 2},
Kai Guo⁷,
Kaixin Li⁷,
Xiaona Zhang⁷,
Chong Wang^{1, 2, 7},
Chunshuang Chu³,
Kangkai Tian³,
Haoyan Liu^{1, 2},
Yonghui Zhang^{1, 2,},
Naixin Liu^{5, 7,},
Zi-Hui Zhang^{1, 3, 4},
Jianchang Yan^{5, 6}

1.
State Key Laboratory of Reliability and Intelligence of Electrical Equipment, School of Electronics and Information Engineering, University Hebei of Technology, Tianjin 300401, China
2.
Key Laboratory of Electronic Materials and Devices of Tianjin, 5340 Xiping Road, Beichen District, Tianjin 300401, China
3.
School of Integrated Circuits, Guangdong University of Technology, 100 Waihuan West Road, Fanyu District, Guangzhou City, Guangdong Province, 510006, China
4.
Tianjin San'an Optoelectronics Co., Ltd, Tianjin 300450, China
5.
The Research and Development Center for Wide Bandgap Semiconductors Institute of Semiconductors Chinese Academy of Sciences, Beijing 100083, China
6.
School of Integrated Circuit Science and Engineering, Beihang University
7.
Shanxi Semiconductor Deep Ultraviolet Technology Innovation Center, Advanced Ultraviolet Optoelectronics Company Ltd, and Shanxi Zhongke Lu'an Semiconductor Technology Research Institute Co., Ltd, Changzhi, Shanxi 046000, China

More Information

Yifei Dong got his bachelor's degree in 2024 from Hebei University of Technology. Now he is a master's student at Hebei University of Technology under the supervision of Prof. Yonghui Zhang. His research focuses on the fabrication of AlGaN-based deep-ultraviolet light-emitting diodes
Yonghui Zhang received his doctoral degree from the Institute of Semiconductors in 2015. He is currently a Professor at Hebei University of Technology, Tianjin, China. His current research interests include simulation, design, and fabrication of third-generation semiconductor optoelectronic devices
Naixin Liu received his doctoral degree from the Institute of Semiconductors in 2009. He is currently an Associate Professor with the Institute of Semiconductors, Chinese Academy of Sciences, Beijing, China. His current research interests include epitaxial growth of wide-bandgap nitride semiconductor materials and light-emitting devices
Corresponding author: zhangyh@hebut.edu.cn; nxliu@semi.ac.cn
Received Date: 2026-03-17
Revised Date: 2026-05-12

Available Online: 2026-06-03

Abstract

Abstract

Electrode design is critical for the performance and reliability of flip-chip AlGaN-based deep-ultraviolet light-emitting diodes (DUV LEDs). We propose a semi-surround n-electrode design to achieve better current spreading for a relatively small DUV LED with a size of 8×15 mil². It is found that an optimal semi-surround n-electrode can reduce the operating voltage and increase the chip reliability due to the larger ohmic contact area. Moreover, the semi-surround n-electrode introduces multiple current injection paths, which causes the improvement of the current spreading in both the directions parallel (X) and perpendicular (Y) to the electrode fingers. However, an excessively long semi-surround n-electrode will decrease the light output power because of the severely reduced active region area. Furthermore, experiments and simulations reveal that the semi-surround n-electrode can improve the current spreading in the Y direction at high injection current. Meanwhile, it is also found that a short semi-surround n-electrode causes deteriorated current spreading in the X direction due to the unbalanced resistance between n-electrode and p-electrode. Our work highlights the importance of two-dimensional current management in electrode design and provides a practical strategy for developing high-performance and reliable DUV LEDs with a relatively small chip size.
- DUV LEDs,
- current spreading,
- semi-surround n-electrode.

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References(18)