J. Semicond. > 2022, Volume 43 > Issue 6 > 062801

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A 10 × 10 deep ultraviolet light-emitting micro-LED array

Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Haochen Zhang, Meng Tian, Shi Fang, Danhao Wang, Yang Kang, Shudan Xiao, Shibing Long and Haiding Sun

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 Corresponding author: Haiding Sun, haiding@ustc.edu.cn

DOI: 10.1088/1674-4926/43/6/062801

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Abstract: In this work, we design and fabricate a deep ultraviolet (DUV) light-emitting array consisting of 10 × 10 micro-LEDs (μ-LEDs) with each device having 20 μm in diameter. Strikingly, the array demonstrates a significant enhancement of total light output power by nearly 52% at the injection current of 100 mA, in comparison to a conventional large LED chip whose emitting area is the same as the array. A much higher (~22%) peak external quantum efficiency, as well as a smaller efficiency droop for μ-LED array, was also achieved. The numerical calculation reveals that the performance boost can be attributed to the higher light extraction efficiency at the edge of each μ-LED. Additionally, the far-field pattern measurement shows that the μ-LED array possesses a better forward directionality of emission. These findings shed light on the enhancement of the DUV LEDs performance and provide new insights in controlling the light behavior of the μ-LEDs.

Key words: AlGaNdeep ultravioletmicro-LED arraylight extraction efficiency



[1]
Zhang H C, Huang C, Song K, et al. Compositionally graded III-nitride alloys: Building blocks for efficient ultraviolet optoelectronics and power electronics. Rep Prog Phys, 2021, 84, 044401 doi: 10.1088/1361-6633/abde93
[2]
Kneissl M, Seong T Y, Han J, et al. The emergence and prospects of deep-ultraviolet light-emitting diode technologies. Nat Photonics, 2019, 13, 233 doi: 10.1038/s41566-019-0359-9
[3]
Inagaki H, Saito A, Sugiyama H, et al. Rapid inactivation of SARS-CoV-2 with deep-UV LED irradiation. Emerg Microbes Infect, 2020, 9, 1744 doi: 10.1080/22221751.2020.1796529
[4]
Ren Z J, Yu H B, Liu Z L, et al. Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: A review. J Phys D, 2020, 53, 073002 doi: 10.1088/1361-6463/ab4d7b
[5]
Guttmann M, Susilo A, Sulmoni L, et al. Light extraction efficiency and internal quantum efficiency of fully UVC-transparent AlGaN based LEDs. J Phys D, 2021, 54, 335101 doi: 10.1088/1361-6463/ac021a
[6]
Zheng Z H, Chen Q, Dai J N, et al. Enhanced light extraction efficiency via double nano-pattern arrays for high-efficiency deep UV LEDs. Opt Laser Technol, 2021, 143, 107360 doi: 10.1016/j.optlastec.2021.107360
[7]
Zhang J, Zhao H P, Tansu N. Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers. Appl Phys Lett, 2010, 97, 111105 doi: 10.1063/1.3488825
[8]
Floyd R, Hussain K, Mamun A, et al. Photonics integrated circuits using Al xGa1– xN based UVC light-emitting diodes, photodetectors and waveguides. Appl Phys Express, 2020, 13, 022003 doi: 10.7567/1882-0786/ab6410
[9]
Peng X C, Guo W, Xu H Q, et al. Significantly boosted external quantum efficiency of AlGaN-based DUV-LED utilizing thermal annealed Ni/Al reflective electrodes. Appl Phys Express, 2021, 14, 072005 doi: 10.35848/1882-0786/ac0b07
[10]
Zhou S, Liu X, Gao Y, et al. Numerical and experimental investigation of GaN-based flip-chip light-emitting diodes with highly reflective Ag/TiW and ITO/DBR Ohmic contacts. Opt Express, 2017, 25, 26615 doi: 10.1364/OE.25.026615
[11]
Zheng Y, Zhang Y, Zhang J, et al. Effects of meshed p-type contact structure on the light extraction effect for deep ultraviolet flip-chip light-emitting diodes. Nanoscale Res Lett, 2019, 14, 149 doi: 10.1186/s11671-019-2984-0
[12]
Zhang G, Shao H, Zhang M Y, et al. Enhancing the light extraction efficiency for AlGaN-based DUV LEDs with a laterally over-etched p-GaN layer at the top of truncated cones. Opt Express, 2021, 29, 30532 doi: 10.1364/OE.435302
[13]
Shin W, Pandey A, Liu X, et al. Photonic crystal tunnel junction deep ultraviolet light emitting diodes with enhanced light extraction efficiency. Opt Express, 2019, 27, 38413 doi: 10.1364/OE.380739
[14]
Liang R L, Dai J N, Xu L L, et al. High light extraction efficiency of deep ultraviolet LEDs enhanced using nanolens arrays. IEEE Trans Electron Devices, 2018, 65, 2498 doi: 10.1109/TED.2018.2823742
[15]
Inoue S I, Naoki T, Kinoshita T, et al. Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure. Appl Phys Lett, 2015, 106, 131104 doi: 10.1063/1.4915255
[16]
Ooi Y K, Zhang J. Light extraction efficiency analysis of flip-chip ultraviolet light-emitting diodes with patterned sapphire substrate. IEEE Photonics J, 2018, 10, 1 doi: 10.1109/JPHOT.2018.2847226
[17]
Manley P, Walde S, Hagedorn S, et al. Nanopatterned sapphire substrates in deep-UV LEDs: Is there an optical benefit. Opt Express, 2020, 28, 3619 doi: 10.1364/OE.379438
[18]
Yu H, Jia H, Liu Z, et al. Development of highly efficient ultraviolet LEDs on hybrid patterned sapphire substrates. Opt Lett, 2021, 46, 5356 doi: 10.1364/OL.441300
[19]
Hu H P, Tang B, Wan H, et al. Boosted ultraviolet electroluminescence of InGaN/AlGaN quantum structures grown on high-index contrast patterned sapphire with silica array. Nano Energy, 2020, 69, 104427 doi: 10.1016/j.nanoen.2019.104427
[20]
Zhang C, Tang N, Shang L L, et al. Local surface plasmon enhanced polarization and internal quantum efficiency of deep ultraviolet emissions from AlGaN-based quantum wells. Sci Rep, 2017, 7, 2358 doi: 10.1038/s41598-017-02590-7
[21]
Zhou S J, Xu H H, Tang B, et al. High-power and reliable GaN-based vertical light-emitting diodes on 4-inch silicon substrate. Opt Express, 2019, 27, A1506 doi: 10.1364/OE.27.0A1506
[22]
Chen Q, Zhang H X, Dai J N, et al. Enhanced the optical power of AlGaN-based deep ultraviolet light-emitting diode by optimizing mesa sidewall angle. IEEE Photonics J, 2018, 10, 1 doi: 10.1109/JPHOT.2018.2850038
[23]
Lee J W, Park J H, Kim D Y, et al. Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission. ACS Photonics, 2016, 3, 2030 doi: 10.1021/acsphotonics.6b00572
[24]
Zhang J, Chang L, Zheng Y, et al. Integrating remote reflector and air cavity into inclined sidewalls to enhance the light extraction efficiency for AlGaN-based DUV LEDs. Opt Express, 2020, 28, 17035 doi: 10.1364/OE.393166
[25]
Tian M, Yu H, Memon M H, et al. Enhanced light extraction of the deep-ultraviolet micro-LED via rational design of chip sidewall. Opt Lett, 2021, 46, 4809 doi: 10.1364/OL.441285
[26]
Yu H, Memon M H, Wang D, et al. AlGaN-based deep ultraviolet micro-LED emitting at 275 nm. Opt Lett, 2021, 46, 3271 doi: 10.1364/OL.431933
[27]
Floyd R, Gaevski M, Hussain K, et al. Enhanced light extraction efficiency of micropixel geometry AlGaN DUV light-emitting diodes. Appl Phys Express, 2021, 14, 084002 doi: 10.35848/1882-0786/ac0fb8
[28]
Floyd R, Gaevski M, Alam M D, et al. An opto-thermal study of high brightness 280 nm emission AlGaN micropixel light-emitting diode arrays. Appl Phys Express, 2021, 14, 014002 doi: 10.35848/1882-0786/abd140
[29]
Ley R T, Smith J M, Wong M S, et al. Revealing the importance of light extraction efficiency in InGaN/GaN microLEDs via chemical treatment and dielectric passivation. Appl Phys Lett, 2020, 116, 251104 doi: 10.1063/5.0011651
[30]
Zhang S, Liu Y, Zhang J, et al. Optical polarization characteristics and light extraction behavior of deep-ultraviolet LED flip-chip with full-spatial omnidirectional reflector system. Opt Express, 2019, 27, A1601 doi: 10.1364/OE.27.0A1601
[31]
Wei T B, Wu K, Lan D, et al. Selectively grown photonic crystal structures for high efficiency InGaN emitting diodes using nanospherical-lens lithography. Appl Phys Lett, 2012, 101, 211111 doi: 10.1063/1.4767334
Fig. 1.  (Color online) (a) Schematic of a fabricated DUV μ-LED array and (b) its cross-section of the DUV μ-LED array and (c) the profile of the sidewall and θ is the inclination angle of the sidewall.

Fig. 2.  (Color online) (a) The current–voltage (IV) characteristic of the DUV LEDs. The inset shows the corresponding logarithmic plot. (b) The spectra of the DUV LEDs operating at the driving current of 100 mA.

Fig. 3.  (Color online) (a) The light output power (LOP), (b) the external quantum efficiency (EQE), (c) the wall-plug efficiency, and (d) the LEE enhancement factor of the DUV LEDs at different currents for the three investigated devices.

Fig. 4.  (Color online) Electric field distributions for the light propagation paths of the TM-polarized light when the dipole source at (a) the center of the mesa and (b) the edge of the mesa. The LEEs for the (c) TE- and (d) TM-polarized light as a function of the position of the dipole source for the C-LED, μ-LED (50 μm), and μ-LED (20 μm), respectively. The insets of the (c) and (d) are the device schematic which indicates the position change of the dipole source.

Fig. 5.  (Color online) (a) Far-field patterns for the C-LED, the μ-LED array (50 μm), and the μ-LED array (20 μm) at 100 mA. (b) The divergence angle of the far-field patterns. The schematic illustrations of light propagation characteristics in (c) the C-LED and (d) the μ-LED array.

[1]
Zhang H C, Huang C, Song K, et al. Compositionally graded III-nitride alloys: Building blocks for efficient ultraviolet optoelectronics and power electronics. Rep Prog Phys, 2021, 84, 044401 doi: 10.1088/1361-6633/abde93
[2]
Kneissl M, Seong T Y, Han J, et al. The emergence and prospects of deep-ultraviolet light-emitting diode technologies. Nat Photonics, 2019, 13, 233 doi: 10.1038/s41566-019-0359-9
[3]
Inagaki H, Saito A, Sugiyama H, et al. Rapid inactivation of SARS-CoV-2 with deep-UV LED irradiation. Emerg Microbes Infect, 2020, 9, 1744 doi: 10.1080/22221751.2020.1796529
[4]
Ren Z J, Yu H B, Liu Z L, et al. Band engineering of III-nitride-based deep-ultraviolet light-emitting diodes: A review. J Phys D, 2020, 53, 073002 doi: 10.1088/1361-6463/ab4d7b
[5]
Guttmann M, Susilo A, Sulmoni L, et al. Light extraction efficiency and internal quantum efficiency of fully UVC-transparent AlGaN based LEDs. J Phys D, 2021, 54, 335101 doi: 10.1088/1361-6463/ac021a
[6]
Zheng Z H, Chen Q, Dai J N, et al. Enhanced light extraction efficiency via double nano-pattern arrays for high-efficiency deep UV LEDs. Opt Laser Technol, 2021, 143, 107360 doi: 10.1016/j.optlastec.2021.107360
[7]
Zhang J, Zhao H P, Tansu N. Effect of crystal-field split-off hole and heavy-hole bands crossover on gain characteristics of high Al-content AlGaN quantum well lasers. Appl Phys Lett, 2010, 97, 111105 doi: 10.1063/1.3488825
[8]
Floyd R, Hussain K, Mamun A, et al. Photonics integrated circuits using Al xGa1– xN based UVC light-emitting diodes, photodetectors and waveguides. Appl Phys Express, 2020, 13, 022003 doi: 10.7567/1882-0786/ab6410
[9]
Peng X C, Guo W, Xu H Q, et al. Significantly boosted external quantum efficiency of AlGaN-based DUV-LED utilizing thermal annealed Ni/Al reflective electrodes. Appl Phys Express, 2021, 14, 072005 doi: 10.35848/1882-0786/ac0b07
[10]
Zhou S, Liu X, Gao Y, et al. Numerical and experimental investigation of GaN-based flip-chip light-emitting diodes with highly reflective Ag/TiW and ITO/DBR Ohmic contacts. Opt Express, 2017, 25, 26615 doi: 10.1364/OE.25.026615
[11]
Zheng Y, Zhang Y, Zhang J, et al. Effects of meshed p-type contact structure on the light extraction effect for deep ultraviolet flip-chip light-emitting diodes. Nanoscale Res Lett, 2019, 14, 149 doi: 10.1186/s11671-019-2984-0
[12]
Zhang G, Shao H, Zhang M Y, et al. Enhancing the light extraction efficiency for AlGaN-based DUV LEDs with a laterally over-etched p-GaN layer at the top of truncated cones. Opt Express, 2021, 29, 30532 doi: 10.1364/OE.435302
[13]
Shin W, Pandey A, Liu X, et al. Photonic crystal tunnel junction deep ultraviolet light emitting diodes with enhanced light extraction efficiency. Opt Express, 2019, 27, 38413 doi: 10.1364/OE.380739
[14]
Liang R L, Dai J N, Xu L L, et al. High light extraction efficiency of deep ultraviolet LEDs enhanced using nanolens arrays. IEEE Trans Electron Devices, 2018, 65, 2498 doi: 10.1109/TED.2018.2823742
[15]
Inoue S I, Naoki T, Kinoshita T, et al. Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure. Appl Phys Lett, 2015, 106, 131104 doi: 10.1063/1.4915255
[16]
Ooi Y K, Zhang J. Light extraction efficiency analysis of flip-chip ultraviolet light-emitting diodes with patterned sapphire substrate. IEEE Photonics J, 2018, 10, 1 doi: 10.1109/JPHOT.2018.2847226
[17]
Manley P, Walde S, Hagedorn S, et al. Nanopatterned sapphire substrates in deep-UV LEDs: Is there an optical benefit. Opt Express, 2020, 28, 3619 doi: 10.1364/OE.379438
[18]
Yu H, Jia H, Liu Z, et al. Development of highly efficient ultraviolet LEDs on hybrid patterned sapphire substrates. Opt Lett, 2021, 46, 5356 doi: 10.1364/OL.441300
[19]
Hu H P, Tang B, Wan H, et al. Boosted ultraviolet electroluminescence of InGaN/AlGaN quantum structures grown on high-index contrast patterned sapphire with silica array. Nano Energy, 2020, 69, 104427 doi: 10.1016/j.nanoen.2019.104427
[20]
Zhang C, Tang N, Shang L L, et al. Local surface plasmon enhanced polarization and internal quantum efficiency of deep ultraviolet emissions from AlGaN-based quantum wells. Sci Rep, 2017, 7, 2358 doi: 10.1038/s41598-017-02590-7
[21]
Zhou S J, Xu H H, Tang B, et al. High-power and reliable GaN-based vertical light-emitting diodes on 4-inch silicon substrate. Opt Express, 2019, 27, A1506 doi: 10.1364/OE.27.0A1506
[22]
Chen Q, Zhang H X, Dai J N, et al. Enhanced the optical power of AlGaN-based deep ultraviolet light-emitting diode by optimizing mesa sidewall angle. IEEE Photonics J, 2018, 10, 1 doi: 10.1109/JPHOT.2018.2850038
[23]
Lee J W, Park J H, Kim D Y, et al. Arrays of truncated cone AlGaN deep-ultraviolet light-emitting diodes facilitating efficient outcoupling of in-plane emission. ACS Photonics, 2016, 3, 2030 doi: 10.1021/acsphotonics.6b00572
[24]
Zhang J, Chang L, Zheng Y, et al. Integrating remote reflector and air cavity into inclined sidewalls to enhance the light extraction efficiency for AlGaN-based DUV LEDs. Opt Express, 2020, 28, 17035 doi: 10.1364/OE.393166
[25]
Tian M, Yu H, Memon M H, et al. Enhanced light extraction of the deep-ultraviolet micro-LED via rational design of chip sidewall. Opt Lett, 2021, 46, 4809 doi: 10.1364/OL.441285
[26]
Yu H, Memon M H, Wang D, et al. AlGaN-based deep ultraviolet micro-LED emitting at 275 nm. Opt Lett, 2021, 46, 3271 doi: 10.1364/OL.431933
[27]
Floyd R, Gaevski M, Hussain K, et al. Enhanced light extraction efficiency of micropixel geometry AlGaN DUV light-emitting diodes. Appl Phys Express, 2021, 14, 084002 doi: 10.35848/1882-0786/ac0fb8
[28]
Floyd R, Gaevski M, Alam M D, et al. An opto-thermal study of high brightness 280 nm emission AlGaN micropixel light-emitting diode arrays. Appl Phys Express, 2021, 14, 014002 doi: 10.35848/1882-0786/abd140
[29]
Ley R T, Smith J M, Wong M S, et al. Revealing the importance of light extraction efficiency in InGaN/GaN microLEDs via chemical treatment and dielectric passivation. Appl Phys Lett, 2020, 116, 251104 doi: 10.1063/5.0011651
[30]
Zhang S, Liu Y, Zhang J, et al. Optical polarization characteristics and light extraction behavior of deep-ultraviolet LED flip-chip with full-spatial omnidirectional reflector system. Opt Express, 2019, 27, A1601 doi: 10.1364/OE.27.0A1601
[31]
Wei T B, Wu K, Lan D, et al. Selectively grown photonic crystal structures for high efficiency InGaN emitting diodes using nanospherical-lens lithography. Appl Phys Lett, 2012, 101, 211111 doi: 10.1063/1.4767334
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    Received: 29 November 2021 Revised: 23 December 2021 Online: Uncorrected proof: 12 February 2022Accepted Manuscript: 12 February 2022Published: 06 June 2022

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      Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Haochen Zhang, Meng Tian, Shi Fang, Danhao Wang, Yang Kang, Shudan Xiao, Shibing Long, Haiding Sun. A 10 × 10 deep ultraviolet light-emitting micro-LED array[J]. Journal of Semiconductors, 2022, 43(6): 062801. doi: 10.1088/1674-4926/43/6/062801 ****Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Haochen Zhang, Meng Tian, Shi Fang, Danhao Wang, Yang Kang, Shudan Xiao, Shibing Long, Haiding Sun, A 10 × 10 deep ultraviolet light-emitting micro-LED array[J]. Journal of Semiconductors, 2022, 43(6), 062801 doi: 10.1088/1674-4926/43/6/062801
      Citation:
      Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Haochen Zhang, Meng Tian, Shi Fang, Danhao Wang, Yang Kang, Shudan Xiao, Shibing Long, Haiding Sun. A 10 × 10 deep ultraviolet light-emitting micro-LED array[J]. Journal of Semiconductors, 2022, 43(6): 062801. doi: 10.1088/1674-4926/43/6/062801 ****
      Huabin Yu, Muhammad Hunain Memon, Hongfeng Jia, Haochen Zhang, Meng Tian, Shi Fang, Danhao Wang, Yang Kang, Shudan Xiao, Shibing Long, Haiding Sun, A 10 × 10 deep ultraviolet light-emitting micro-LED array[J]. Journal of Semiconductors, 2022, 43(6), 062801 doi: 10.1088/1674-4926/43/6/062801

      A 10 × 10 deep ultraviolet light-emitting micro-LED array

      DOI: 10.1088/1674-4926/43/6/062801
      More Information
      • Huabin Yu:received the BEng degree from University of Science and Technology of Beijing, Beijing, China, in 2019. He is pursuing the PhDdegree with the School of Microelectronics, University of Science and Technology of China, Hefei, China
      • Haiding Sun:received the BS degree from Huazhong University of Science and Technology, Wuhan, China, in 2008, and the PhD degree in electrical engineering from Boston University, Boston, MA, United States, in 2015. He is currently a professor with the School of Microelectronics, University of Science and Technology of China, Hefei, China. His research interests include the investigation of the physics, MBE and MOCVD epitaxy, fabrication, and characterization of semiconductor materials and devices
      • Corresponding author: haiding@ustc.edu.cn
      • Received Date: 2021-11-29
      • Accepted Date: 2022-02-10
      • Revised Date: 2021-12-23
      • Available Online: 2022-05-20

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