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The emergence and prospects of deep-ultraviolet light-emitting diode technologies

Nature Photonics volume 13, pages 233–244 (2019)Cite this article

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Abstract

By alloying GaN with AlN the emission of AlGaN light-emitting diodes can be tuned to cover almost the entire ultraviolet spectral range (210–400 nm), making ultraviolet light-emitting diodes perfectly suited to applications across a wide number of fields, whether biological, environmental, industrial or medical. However, technical developments notwithstanding, deep-ultraviolet light-emitting diodes still exhibit relatively low external quantum efficiencies because of properties intrinsic to aluminium-rich group III nitride materials. Here, we review recent progress in the development of AlGaN-based deep-ultraviolet light-emitting devices. We also describe the key obstacles to enhancing their efficiency and how to improve their performance in terms of defect density, carrier-injection efficiency, light extraction efficiency and heat dissipation.

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Fig. 1: Applications of UVA, UVB and UVC LEDs.
Fig. 2: EQEs for group-III-nitride-based LEDs.
Fig. 3: Schematic of an AlGaN MQW DUV LED heterostructure, cross-sectional TEM of epitaxial lateral overgrowth of AlN/sapphire, and relationship between IQE and TDD.
Fig. 4: Schematic band diagram of a DUV LED, different designs for EBLs, polarization of the emission from AlGaN QWs, and light output characteristics of an UVC LED with enhanced LEE.
Fig. 5: WPEs of commercial DUV LEDs.

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References

  1. Akasaki, I., Amano, H., Hiramatsu, K. & Sawaki, N. High efficiency blue LED utilizing GaN film with AlN buffer layer grown by MOVPE. Proc. 14th Int. Symp. Gallium Arsenide and Related Compounds 1987, 633–636 (1988).

    Google Scholar 

  2. Amano, H. & Akasaki, I. GaN blue and ultraviolet light emitting devices. Solid State Phys. 25, 399–405 (1990).

    Google Scholar 

  3. Nakamura, S., Mukai, T. & Senoh, M. Candela-class high-brightness InGaN/AlGaN double-heterostructure blue-light-emitting diodes. Appl. Phys. Lett. 64, 1687–1689 (1994).

    ADS  Google Scholar 

  4. Narukawa, Y., Ichikawa, M., Sanga, D., Sano, M. & Mukai, T. White light emitting diodes with super-high luminous efficacy. J. Phys. D 43, 354002 (2010).

    Google Scholar 

  5. Kneissl, M. & Rass, J. (eds) III-Nitride Ultraviolet Emitters–Technology and Applications (Springer, 2016).

  6. Kowalski, W. Ultraviolet Germicidal Irradiation Handbook (Springer, 2009).

  7. Crawford, M. H. et al. Final LDRD Report: Ultraviolet Water Purification Systems for Rural Environments and Mobile Applications Sandia Report SAND2005-7245 (Sandia National Laboratories, 2005).

  8. Würtele, M.-A. et al. Application of GaN-based deep ultraviolet light emitting diodes–UV LEDs for water disinfection. Water Res. 45, 1481–1489 (2011).

    Google Scholar 

  9. Neckers, D. C. et al. Performance of the light emitting diodes versus conventional light sources in the UV light cured formulations. J. Appl. Polym. Sci. 105, 803–808 (2007).

    Google Scholar 

  10. Endruweit, A. et al. Curing of composite components by ultraviolet radiation: a review. Polym. Comp. 27, 119–128 (2006).

    Google Scholar 

  11. Decker, C. et al. The use of UV irradiation in polymerization. Polym. Int. 45, 133–141 (1998).

    Google Scholar 

  12. Schreiner, M., Martínez-Abaigar, J., Glaab, J. & Jansen, M. UVB induced secondary plant metabolites. Opt. Photon. 9, 34–37 (2014).

    Google Scholar 

  13. Hockberger, P. E. A history of ultraviolet photobiology for humans, animals and microorganisms. Photochem. Photobiol. 76, 561–579 (2002).

    Google Scholar 

  14. Hargis, P.-J. Jr, Sobering, T.-J., Tisone, G.-C. & Wagner, J.-S. Ultraviolet fluorescence detection and identification of protein. DNA, and bacteria. Proc. SPIE 2366, 147–153 (1995).

    Google Scholar 

  15. Mellqvist, J. & Rosen, A. DOAS for flue gas monitoring—I. Temperature effects in the UV/visible absorption spectra of NO, NO2, SO2 and NH3. J. Quant. Spectrosc. Radiat. Transf. 56, 187–208 (1996).

    ADS  Google Scholar 

  16. Hodgkinson, J. & Tatam, R.-P. Optical gas sensing: a review. Meas. Sci. Technol. 24, 012004 (2013).

    ADS  Google Scholar 

  17. Tsuzuki, H. et al. High-performance UV emitter grown on high-crystalline quality AlGaN underlying layer. Phys. Status Solidi (a) 206, 1199–1204 (2009).

    ADS  Google Scholar 

  18. Zhang, J. et al. AlGaN deep-ultraviolet light-emitting diodes. Jpn. J. Appl. Phys. 44, 7250–7253 (2005).

    ADS  Google Scholar 

  19. Khan, A., Balakrishnan, K. & Katona, T. Ultraviolet light-emitting diodes based on group three nitrides. Nat. Photon. 2, 77–84 (2008).

    ADS  Google Scholar 

  20. Hirayama, H. et al. 222–282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on high-quality AlN on sapphire. Phys. Status Solidi (a) 206, 1176–1182 (2009).

    ADS  Google Scholar 

  21. Hirayama, H., Tsukada, Y., Maeda, Y. & Kamata, N. Marked enhancement in the efficiency of deep-ultraviolet AlGaN light-emitting diodes by using a multiquantum-barrier electron blocking layer. Appl. Phys. Express 3, 031002 (2010).

    ADS  Google Scholar 

  22. Pernot, C. et al. Improved efficiency of 255–280 nm AlGaN-based light-emitting diodes. Appl. Phys. Express 3, 061004 (2010).

    ADS  Google Scholar 

  23. Grandusky, J. R. et al. High output power from 260 nm pseudomorphic ultraviolet light-emitting diodes with improved thermal performance. Appl. Phys. Express 4, 082101 (2011).

    ADS  Google Scholar 

  24. Kneissl, M. et al. Advances in group III-nitride based deep UV light emitting diode technology. Semicond. Sci. Technol. 26, 014036 (2011).

    ADS  Google Scholar 

  25. Shatalov, M. et al. AlGaN deep-ultraviolet light-emitting diodes with external quantum efficiency above 10%. Appl. Phys. Express 5, 082101 (2012).

    ADS  Google Scholar 

  26. Kinoshita, T. et al. Performance and reliability of deep-ultraviolet light-emitting diodes fabricated on AlN substrates prepared by hydride vapor phase epitaxy. Appl. Phys. Express 6, 092103 (2013).

    ADS  Google Scholar 

  27. Grandusky, J. R. et al. 270 nm pseudomorphic ultraviolet light-emitting diodes with over 60 mW continuous wave output power. Appl. Phys. Express 6, 032101 (2013).

    ADS  Google Scholar 

  28. Mehnke, F. et al. Efficient charge carrier injection into sub-250 nm AlGaN multiple quantum well light emitting diodes. Appl. Phys. Lett. 105, 051113 (2014).

    ADS  Google Scholar 

  29. Takano, T. et al. Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275 nm achieved by improving light-extraction efficiency. Appl. Phys. Express 10, 031002 (2017).

    ADS  Google Scholar 

  30. Inoue, S., Tamari, N. & Taniguchi, M. 150 mW deep-ultraviolet light-emitting diodes with large-area AlN nanophotonic light-extraction structure emitting at 265 nm. Appl. Phys. Lett. 110, 141106 (2017).

    ADS  Google Scholar 

  31. Choi, R. Current status and future works of high-power deep UV LEDs. Proc SPIE 10104, 101041N (2017).

    Google Scholar 

  32. LG Innotek unveils the world’s first ‘100mW’ UV-C LED https://go.nature.com/2Tr4q3k (LG Innotek, 27 November 2017).

  33. Hirayama, H. et al. Over 10% EQE AlGaN deep-UV LED using transparent p-AlGaN contact layer. Proc. SPIE 10104, 101041P (2017).

  34. Scheidt, P. Thermal management of LED technology in applications. LED Profession. Rev. 4, 19–21 (2007).

    Google Scholar 

  35. Meneghini, M., Barbisan, D., Rodighiero, L., Meneghesso, G. & Zanoni, E. Analysis of the physical processes responsible for the degradation of deep-ultraviolet light emitting diodes. Appl. Phys. Lett. 97, 143506 (2010).

    ADS  Google Scholar 

  36. Glaab, J. et al. Degradation effects of the active region in UV-C light-emitting diodes. J. Appl. Phys. 123, 104502 (2018).

    ADS  Google Scholar 

  37. Fujioka, A. et al. High-output-power 255/280/310 nm deep ultraviolet light-emitting diodes and their lifetime characteristics. Semicond. Sci. Technol. 29, 084005 (2014).

    ADS  Google Scholar 

  38. Nagasawa, Y. et al. A review of AlGaN-based deep-ultraviolet light-emitting diodes on sapphire. Appl. Sci. 8, 1264 (2018).

    Google Scholar 

  39. Reentilä, O. et al. Effect of the AlN nucleation layer growth on AlN material quality. J. Cryst. Growth 310, 4932–4934 (2008).

    ADS  Google Scholar 

  40. Mickevičius, J. et al. Internal quantum efficiency in AlGaN with strong carrier localization. Appl. Phys. Lett. 101, 211902 (2012).

    ADS  Google Scholar 

  41. Ban, K. et al. Internal quantum efficiency of whole-composition-range AlGaN multiquantum wells. Appl. Phys. Express 4, 052101 (2011).

    ADS  Google Scholar 

  42. Chichibu, S., Azuhata, T., Sota, T. & Nakamura, S. Luminescences from localized states in InGaN epilayers. Appl. Phys. Lett. 70, 2822–2824 (1997).

    ADS  Google Scholar 

  43. Chichibu, S. F. et al. Origin of defect-insensitive emission probability in In-containing (Al,In,Ga)N alloy semiconductors. Nat. Mater. 5, 810–816 (2006).

    ADS  Google Scholar 

  44. Mickevicius, J. et al. Photoluminescence dynamics of AlGaN quantum wells with built-in electric fields and localized states. Phys. Stat. Sol. (a) 207, 423–427 (2010).

    ADS  Google Scholar 

  45. Jain, R. et al. Migration enhanced lateral epitaxial overgrowth of AlN and AlGaN for high reliability deep ultraviolet light emitting diodes. Appl. Phys. Lett. 93, 051113 (2008).

    ADS  Google Scholar 

  46. Liu, X.-H. et al. Influence of growth temperature on intrinsic stress distribution in aluminum nitride grown by hydride vapor phase epitaxy. Mater. Express 6, 367–370 (2016).

    ADS  Google Scholar 

  47. Huang, C.-Y. et al. High-quality and highly-transparent AlN template on annealed sputter-deposited AlN buffer layer for deep ultra-violet light-emitting diodes. AIP Adv. 7, 055110 (2017).

    ADS  Google Scholar 

  48. Kueller, V. et al. (Al,Ga)N overgrowth over AlN ridges oriented in [1120] and [1100] direction. Phys. Status Solidi (c) 8, 2022–2024 (2011).

    ADS  Google Scholar 

  49. Kawashima, T. et al. High-quality Al0.12Ga0.88N film with low dislocation density grown on facet-controlled Al0.12Ga0.88N by MOVPE. J. Cryst. Growth 272, 377–380 (2004).

    ADS  Google Scholar 

  50. Susilo, N. et al. AlGaN-based deep UV LEDs grown on sputtered and high temperature annealed AlN/sapphire. Appl. Phys. Lett. 112, 041110 (2018).

    ADS  Google Scholar 

  51. Lin, B. C. et al. Performance enhancement of GaN-based flip-chip ultraviolet light-emitting diodes with a RPD AlN nucleation layer on patterned sapphire substrate. Opt. Mater. Express 4, 1632–1639 (2014).

    ADS  Google Scholar 

  52. Lee, C.-Y. et al. Efficiency improvement of GaN-based ultraviolet light-emitting diodes with reactive plasma deposited AlN nucleation layer on patterned sapphire substrate. Nanoscale Res. Lett. 9, 505 (2014).

    ADS  Google Scholar 

  53. Yan, J. et al. AlGaN-based deep-ultraviolet light-emitting diodes grown on high-quality AlN template using MOVPE. J. Cryst. Growth 414, 254–257 (2015).

    ADS  Google Scholar 

  54. Al Tahtamouni, T. M., Lin, J. Y. & Jiang, H. X. Effects of double layer AlN buffer layers on properties of Si-doped AlxGa1–xN for improved performance of deep ultraviolet light emitting diodes. J. Appl. Phys. 113, 123501 (2013).

    ADS  Google Scholar 

  55. Miyake, H. et al. Annealing of an AlN buffer layer in N2–CO for growth of a high-quality AlN film on sapphire. Appl. Phys. Express 9, 025501 (2016).

    ADS  Google Scholar 

  56. Lee, D. et al. Improved performance of AlGaN-based deep ultraviolet light-emitting diodes with nano-patterned AlN/sapphire substrates. Appl. Phys. Lett. 110, 191103 (2017).

    ADS  Google Scholar 

  57. Kim, J., Pyeon, J., Jeon, M. & Nam, O. Growth and characterization of high quality AlN using combined structure of low temperature buffer and superlattices for applications in the deep ultraviolet. Jpn. J. Appl. Phys. 54, 081001 (2015).

    ADS  Google Scholar 

  58. Wang, T.-Y., Tasi, C.-T., Lin, C.-F. & Wuu, D.-S. 85% internal quantum efficiency of 280-nm AlGaN multiple quantum wells by defect engineering. Sci. Rep. 7, 14422 (2017).

    ADS  Google Scholar 

  59. Heying, B. et al. Role of threading dislocation structure on the x-ray diffraction peak widths in epitaxial GaN films. Appl. Phys. Lett. 68, 643–645 (1996).

    ADS  Google Scholar 

  60. Lee, S. R. et al. Effect of threading dislocations on the Bragg peakwidths of GaN, AlGaN, and AlN heterolayers. Appl. Phys. Lett. 86, 241904 (2005).

    ADS  Google Scholar 

  61. Chierchia, R. et al. Microstructure of heteroepitaxial GaN revealed by x-ray diffraction. J. Appl. Phys. 93, 8918–8925 (2003).

    ADS  Google Scholar 

  62. Hino, T. et al. Characterization of threading dislocations in GaN epitaxial layers. Appl. Phys. Lett. 76, 3421–3423 (2000).

    ADS  Google Scholar 

  63. Kusch, G. et al. Spatial clustering of defect luminescence centers in Si-doped low resistivity Al0.82Ga0.18N. Appl. Phys. Lett. 107, 072103 (2015).

    ADS  Google Scholar 

  64. Bondokov, R. T. et al. Large-area AlN substrates for electronic applications: an industrial perspective. J. Crys. Growth 310, 4020–4026 (2008).

    ADS  Google Scholar 

  65. Ding, K., Avrutin, V., Özgür, Ü. & Morkoç, H. Status of growth of group III-nitride heterostructures for deep ultraviolet light-emitting diodes. Crystals 7, 300 (2017).

    Google Scholar 

  66. Rojo, J. C. et al. Report on the growth of bulk aluminum nitride and subsequent substrate preparation. J. Cryst. Growth 231, 317–321 (2001).

    ADS  Google Scholar 

  67. Hartmann, C., Dittmar, A., Wollweber, J. & Bickermann, M. Bulk AlN growth by physical vapour transport. Semicond. Sci. Technol. 29, 084002 (2014).

    ADS  Google Scholar 

  68. Dalmau, R., Moody, B., Xie, J., Collazo, R. & Sitar, Z. Characterization of dislocation arrays in AlN single crystals grown by PVT. Phys. Status Solidi (a) 208, 1545–1547 (2011).

    ADS  Google Scholar 

  69. Kangawa, Y., Toki, R., Yayama, T., Epelbaum, B. M. & Kakimoto, K. Novel solution growth method of bulk AlN using Al and Li3N solid sources. Appl. Phys. Express 4, 095501 (2011).

    ADS  Google Scholar 

  70. Kumagai, Y., Nagashima, T. & Koukitu, A. Preparation of a freestanding AlN substrate by hydride vapor phase epitaxy at 1230 °C using (111) Si as a starting substrate. Jpn. J. Appl. Phys. 46, L389–L391 (2007).

    ADS  Google Scholar 

  71. Hartmann, C. et al. Preparation of deep UV transparent AlN substrates with high structural perfection for optoelectronic devices. CrystEngComm 18, 3488–3497 (2016).

    Google Scholar 

  72. Nomura, T. et al. AlN homoepitaxial growth on sublimation-AlN substrate by low-pressure HVPE. J. Cryst. Growth 350, 69–71 (2012).

    ADS  Google Scholar 

  73. Irmscher, K. et al. Identification of a tri-carbon defect and its relation to the ultraviolet absorption in aluminum nitride. J. Appl. Phys. 114, 123505 (2013).

    ADS  Google Scholar 

  74. Bryan, Z. et al. High internal quantum efficiency in AlGaN multiple quantum wells grown on bulk AlN substrates. Appl. Phys. Lett. 106, 142107 (2015).

    ADS  Google Scholar 

  75. Karpov, S. U. et al. Dislocation effect on light emission efficiency in gallium nitride. Appl. Phys. Lett. 81, 4721–4723 (2002).

    ADS  Google Scholar 

  76. Hirayama, H. et al. Quaternary InAlGaN-based high-efficiency ultraviolet light-emitting diodes. J. Appl. Phys. 97, 091101 (2005).

    ADS  Google Scholar 

  77. Kaneda, M. et al. Uneven AlGaN multiple quantum well for deep-ultraviolet LEDs grown on macrosteps and impact on electroluminescence spectral output. Jpn. J. Appl. Phys. 56, 061002 (2017).

    ADS  Google Scholar 

  78. Sampath, A. V., Garrett, G. A., Readinger, E. D., Enck, R. W. & Shen, H. Characterization of nanometer scale compositionally inhomogeneous AlGaN active regions on bulk AlN substrates. Solid State Electron. 54, 1130–1134 (2010).

    ADS  Google Scholar 

  79. Murotani, H. et al. Dependence of internal quantum efficiency on doping region and Si concentration in Al-rich AlGaN quantum wells. Appl. Phys. Lett. 101, 042110 (2012).

    ADS  Google Scholar 

  80. Kim, M.-H. et al. Origin of efficiency droop in GaN-based light-emitting diodes. Appl. Phys. Lett. 91, 183507 (2007).

    ADS  Google Scholar 

  81. Taniyasu, Y., Kasu, M. & Kobayashi, N. Intentional control of n-type conduction for Si-doped AlN and AlxGa1-xN (0.42≤x<1). Appl. Phys. Lett. 81, 1255–1257 (2002).

    ADS  Google Scholar 

  82. Nakarmi, M. L., Kim, K. H., Zhu, K., Lin, J. Y. & Jiang, H. X. Transport properties of highly conductive n-type Al-rich AlxGa1-xN (x≥0.7). Appl. Phys. Lett. 85, 3769–3771 (2004).

    ADS  Google Scholar 

  83. Mehnke, F. et al. Highly conductive n-AlxGa1–xN layers with aluminum mole fractions above 80%.Appl. Phys. Lett. 103, 212109 (2013).

    ADS  Google Scholar 

  84. Rajan, S. et al. Electron mobility in graded AlGaN alloys. Appl. Phys. Lett. 88, 042103 (2006).

    ADS  Google Scholar 

  85. Eiting, C. J. et al. P- and N-type doping of GaN and AlGaN epitaxial layers grown by metalorganic chemical vapor deposition. J. Electron. Mater. 27, 206–209 (1998).

    ADS  Google Scholar 

  86. Nagata, N. et al. Reduction of contact resistance in V-based electrode for high AlN molar fraction n-type AlGaN by using thin SiNx intermediate layer. Phys. Status Solidi (c) 14, 1600243 (2017).

  87. Mattila, T. & Nieminen, R. M. Ab initio study of oxygen point defects in GaAs, GaN, and AlN. Phys. Rev. B 54, 16676–16682 (1996).

    ADS  Google Scholar 

  88. Van de Walle, C. G. & Neugebauer, J. First-principles calculations for defects and impurities: applications to III-nitrides. J. Appl. Phys. 95, 3851–3879 (2004).

    ADS  Google Scholar 

  89. Trinh, X. T. et al. Stable and metastable Si negative-U centers in AlGaN and AlN. Appl. Phys. Lett. 105, 162106 (2014).

    ADS  Google Scholar 

  90. Bogusławski, P. & Bernholc, J. Doping properties of C, Si, and Ge impurities in GaN and AlN. Phys. Rev. B 56, 9496–9505 (1997).

    ADS  Google Scholar 

  91. Zhu, S. et al. The effect of delta-doping on Si-doped Al rich n-AlGaN on AlN template grown by MOCVD. Phys. Status Solidi (c) 11, 466–468 (2014).

    ADS  Google Scholar 

  92. Cantu, P., Keller, S., Mishra, U. K. & DenBaars, S. P. Metalorganic chemical vapor deposition of highly conductive Al0.65Ga0.35N films. Appl. Phys. Lett. 82, 3683–3685 (2003).

    ADS  Google Scholar 

  93. Wang, S., Zhang, X., Zhu, M., Li, F. & Cui, Y. Crack-free Si-doped n-AlGaN film grown on sapphire substrate with high-temperature AlN interlayer. Optik 126, 3698–3702 (2015).

    ADS  Google Scholar 

  94. Adhikari, R., Li, T., Capuzzo, G. & Bonanni, A. Controlling a three-dimensional electron slab of graded AlxGa1–xN. Appl. Phys. Lett. 108, 022105 (2016).

    ADS  Google Scholar 

  95. Gordon, L. et al. Hybrid functional calculations of DX centers in AlN and GaN. Phys. Rev. B 89, 085204 (2014).

    ADS  Google Scholar 

  96. Kirste, R. et al. Ge doped GaN with controllable high carrier concentration for plasmonic applications. Appl. Phys. Lett. 103, 242107 (2013).

    ADS  Google Scholar 

  97. Tersoff, J. Theory of semiconductor heterojunctions: the role of quantum dipoles. Phys. Rev. B 30, 4874–4877 (1984).

    ADS  Google Scholar 

  98. Walukiewicz, W. Amphoteric native defects in semiconductors. Appl. Phys. Lett. 54, 2094–2096 (1989).

    ADS  Google Scholar 

  99. Amano, H., Kito, M., Hiramatsu, K. & Akasaki, I. P-type conduction in Mg-doped GaN treated with low-energy electron beam irradiation (LEEBI). Jpn. J. Appl. Phys. 28, L2112–L2114 (1989).

    ADS  Google Scholar 

  100. Nakamura, S. et al. Thermal annealing effects on p-type Mg-doped GaN films. Jpn. J. Appl. Phys. 31, L139–L142 (1992).

    ADS  Google Scholar 

  101. Nam, K. B., Nakarmi, M. L., Li, J., Lin, J. Y. & Jiang, H. X. Mg acceptor level in AlN probed by deep ultraviolet photoluminescence. Appl. Phys. Lett. 83, 878–880 (2003).

    ADS  Google Scholar 

  102. Allerman, A. A., Crawford, M. H., Miller, M. A. & Lee, S. R. Growth and characterization of Mg-doped AlGaN-AlN short-period superlattices for deep-UV optoelectronic devices. J. Crys. Growth 312, 756–761 (2010).

    ADS  Google Scholar 

  103. Zheng, T. C. et al. Improved p-type conductivity in Al-rich AlGaN using multidimensional Mg-doped superlattices. Sci. Rep. 6, 21897 (2016).

    ADS  Google Scholar 

  104. Simon, J., Protasenko, V., Lian, C., Xing, H. & Jena, D. Polarization-induced hole doping in wide-band-gap uniaxial semiconductor heterostructures. Science 327, 60–64 (2010).

    ADS  Google Scholar 

  105. Ebata, K., Nishinaka, J., Taniyasu, Y. & Kumakura, K. High hole concentration in Mg-doped AlN/AlGaN superlattices with high Al content. Jpn. J. Appl. Phys. 57, 04FH09 (2018).

    Google Scholar 

  106. Jeon, S.-R. et al. Investigation of Mg doping in high-Al content p-type AlxGa1–xN (0.3<x<0.5). Appl. Phys. Lett. 86, 082107 (2005).

    ADS  Google Scholar 

  107. Neugebauer, J. & Van de Walle, C. G. Role of hydrogen in doping of GaN. Appl. Phys. Lett. 68, 1829–1831 (1996).

    ADS  Google Scholar 

  108. Kinoshita, T., Obata, T., Yanagi, H. & Inoue, S. High p-type conduction in high-Al content Mg-doped AlGaN. Appl. Phys. Lett. 102, 012105 (2013).

    ADS  Google Scholar 

  109. Aoyagi, Y., Takeuchi, M., Iwai, S. & Hirayama, H. High hole carrier concentration realized by alternative co-doping technique in metal organic chemical vapor deposition. Appl. Phys. Lett. 99, 112110 (2011).

    ADS  Google Scholar 

  110. Nakarmi, M. L., Kim, K. H., Li, J., Lin, J. Y. & Jiang, H. X. Enhanced p-type conduction in GaN and AlGaN by Mg-δ-doping. Appl. Phys. Lett. 82, 3041–3043 (2003).

    ADS  Google Scholar 

  111. Limpijumnong, S. & Van de Walle, C. G. Passivation and doping due to hydrogen in III-nitrides. Phys. Status Solidi (b) 228, 303–307 (2001).

    ADS  Google Scholar 

  112. Myers, S. M. et al. Diffusion, release, and uptake of hydrogen in magnesium-doped gallium nitride: theory and experiment. J. Appl. Phys. 89, 3195–3202 (2001).

    ADS  Google Scholar 

  113. Zvanut, M. E., Sunay, U. R., Dashdorj, J., Willoughby, W. R. & Allerman, A. A. Mg-hydrogen interaction in AlGaN alloys. In Gallium Nitride Materials and Devices VII 8262, 82620L (International Society for Optics and Photonics, 2012).

  114. Dahal, R. et al. Epitaxially grown semiconducting hexagonal boron nitride as a deep ultraviolet photonic material. Appl. Phys. Lett. 98, 211110 (2011).

    ADS  Google Scholar 

  115. Yan, J. et al. Improved performance of UV LED by p-AlGaN with graded composition. Phys. Status Solidi (c) 8, 461–463 (2011).

    ADS  Google Scholar 

  116. Kuo, Y.-K., Chang, J.-Y., Chen, F.-M., Shih, Y.-H. & Chang, H.-T. Numerical investigation on the carrier transport characteristics of AlGaN deep-UV light-emitting diodes. IEEE J. Quantum Electron. 52, 3300105 (2016).

    Google Scholar 

  117. Maeda, N. & Hirayama, H. Realization of high-efficiency deep-UV LEDs using transparent p-AlGaN contact layer. Phys. Status Solidi (c) 10, 1521–1524 (2013).

    ADS  Google Scholar 

  118. Yun, J. & Hirayama, H. Investigation of the light-extraction efficiency in 280nm AlGaN-based light-emitting diodes having a highly transparent p-AlGaN layer. J. Appl. Phys. 121, 013105 (2017).

    ADS  Google Scholar 

  119. Yun, J. et al. Analysis of efficiency droop in 280-nm AlGaN multiple-quantum-well light-emitting diodes based on carrier rate equation. Jpn. J. Appl. Phys. 8, 022104 (2015).

    Google Scholar 

  120. Kuo, Y. K. et al. Simulation and experimental study on barrier thickness of superlattice electron blocking layer in near-ultraviolet light-emitting diodes. IEEE J. Quantum Electron. 52, 3300306 (2016).

    Google Scholar 

  121. Zhang, Y. et al. Interband tunneling for hole injection in III-nitride ultraviolet emitters. Appl. Phys. Lett. 106, 141103 (2015).

    ADS  Google Scholar 

  122. Liang, H. et al. Vertically conducting deep-ultraviolet light-emitting diodes with interband tunneling junction grown on 6H-SiC substrate. Jpn. J. Appl. Phys. 55, 031202 (2016).

    ADS  Google Scholar 

  123. Kuwano, Y. et al. Lateral hydrogen diffusion at p-GaN layers in nitride-based light emitting diodes with tunnel junctions.Jpn. J. Appl. Phys. 52, 08JK12 (2013).

    Google Scholar 

  124. Pankove, J. I., Magee, C. W. & Wance, R. O. Hole-mediated chemisorption of atomic hydrogen in silicon. Appl. Phys. Lett. 47, 748–750 (1985).

    ADS  Google Scholar 

  125. Hirayama, H., Enomoto, Y., Kinoshita, A., Hirata, A. & Aoyagi, Y. Efficient 230–280 nm emission from high-Al-content AlGaN-based multiquantum wells. Appl. Phys. Lett. 80, 37–39 (2002).

    ADS  Google Scholar 

  126. Chang, J.-Y. et al. Effects of quantum barriers and electron-blocking layer in deep-ultraviolet light-emitting diodes. J. Appl. Phys. D 51, 075106 (2018).

    ADS  Google Scholar 

  127. Reich, C. et al. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes. Appl. Phys. Lett. 107, 142101 (2015).

    ADS  Google Scholar 

  128. Lobo, N. et al. Enhancement of light extraction in UV LEDs using nanopixel contact design with Al reflector. Appl. Phys. Lett. 96, 081109 (2010).

    ADS  Google Scholar 

  129. Kashima, Y. et al. High external quantum efficiency (10%) AlGaN-based deep-ultraviolet light-emitting diodes achieved by using highly reflective photonic crystal on p-AlGaN contact layer. Appl. Phys. Express 11, 012101 (2018).

    ADS  Google Scholar 

  130. Nakashima, T. et al. Combination of indium-tin oxide and SiO2/AlN dielectric multilayer reflective electrodes for ultraviolet-light-emitting diodes. Jpn. J. Appl. Phys. 52, 08JG07 (2013).

    Google Scholar 

  131. Oh, S. et al. Self-assembled indium tin oxide nanoball embedded omnidirectional reflectors for high photon extraction efficiency in III-nitride ultraviolet emitters. Nanoscale 9, 7625–7630 (2017).

    Google Scholar 

  132. Inazu, T. et al. Improvement of light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes. Jpn. J. Appl. Phys. 50, 122101 (2011).

    ADS  Google Scholar 

  133. Khizar, M., Fan, Z. Y., Kim, K. H., Lin, J. Y. & Jiang, H. X. Nitride deep-ultraviolet light-emitting diodes with microlens array. Appl. Phys. Lett. 86, 173504 (2005).

    ADS  Google Scholar 

  134. Wierer, J. J., Allerman, A. A., Montaño, I. & Moseley, M. W. Influence of optical polarization on the improvement of light extraction efficiency from reflective scattering structures in AlGaN ultraviolet light-emitting diodes. Appl. Phys. Lett. 105, 061106 (2014).

    ADS  Google Scholar 

  135. Zhang, Y. et al. Effects of inclined sidewall structure with bottom metal air cavity on the light extraction efficiency for AlGaN-based deep ultraviolet light-emitting diodes. IEEE Photon. J. 9, 1600709 (2017).

    Google Scholar 

  136. Gao, N. et al. Surface-plasmon-enhanced deep-UV light emitting diodes based on AlGaN multi-quantum wells. Sci. Rep. 2, 816 (2012).

    Google Scholar 

  137. Wang, J. et al. Localized surface plasmon-enhanced deep-UV light-emitting diodes with Al/Al2O3 asymmetrical nanoparticles. Plasmonics 12, 843–848 (2017).

    Google Scholar 

  138. Long, H. et al. Internal strain induced significant enhancement of deep ultraviolet light extraction efficiency for AlGaN multiple quantum wells grown by MOCVD. Opt. Express 26, 680–685 (2018).

    ADS  Google Scholar 

  139. Adivarahan, V. et al. Vertical injection thin film deep ultraviolet light emitting diodes with AlGaN multiple-quantum wells active region. Appl. Phys. Express 2, 092102 (2009).

    ADS  Google Scholar 

  140. Zhou, L. et al. Vertical injection thin-film multiple-quantum-well deep ultraviolet light emitting diodes. Appl. Phys. Lett. 89, 241113 (2006).

    ADS  Google Scholar 

  141. Aoshima, H. Laser lift-off of AlN/sapphire for UV light-emitting diodes. Phys. Status Solidi (c) 9, 753–756 (2012).

    ADS  Google Scholar 

  142. Lachab, M. et al. Enhancement of light extraction efficiency in sub-300 nm nitride thin-film flip-chip light-emitting diodes. Solid State Electron. 89, 156–160 (2013).

    ADS  Google Scholar 

  143. Ryu, H.-Y., Choi, I.-G., Choi, H.-S. & Shim, J.-I. Investigation of light extraction efficiency in AlGaN deep-ultraviolet light-emitting diodes. Appl. Phys. Express 6, 062101 (2013).

    ADS  Google Scholar 

  144. Shchekin, O. B. et al. High performance thin-film flip-chip InGaN–GaN light-emitting diodes. Appl. Phys. Lett. 89, 071109 (2006).

    ADS  Google Scholar 

  145. Krames, M. R. et al. Status and future of high-power light-emitting diodes for solid-state lighting. J. Display Technol. 3, 160–175 (2007).

    ADS  Google Scholar 

  146. Chitnis, A. et al. High DC power 325 nm emission deep UV LEDs over sapphire. Electron. Lett. 38, 1709–1711 (2002).

    Google Scholar 

  147. Lobo Ploch, N. et al. Effective thermal management in ultraviolet light-emitting diodes with micro-LED arrays. IEEE Trans. Electron Dev. 60, 782–786 (2013).

    ADS  Google Scholar 

  148. Yasan, A. et al. 4.5 mW operation of AlGaN-based 267 nm deep-ultraviolet light-emitting diodes. Appl. Phys. Lett. 83, 4701–4703 (2003).

    ADS  Google Scholar 

  149. Liang, R. et al. Investigation on thermal characterization of eutectic flip-chip UV LEDs with different bonding voidage. IEEE Trans. Electron Dev. 64, 1174–1179 (2017).

    ADS  Google Scholar 

  150. Wang, C.-P., Ying, S.-P., Su, Y.-C. & Chang, T.-L. Thermal analysis of eutectic flip-chip light-emitting diodes fabricated using copper-coated ceramic substrate. IEEE Trans. Electron Dev. 62, 2524–2527 (2015).

    ADS  Google Scholar 

  151. Chitnis, A. et al. Submilliwatt operation of AlInGaN based multifinger-design 315 nm light emitting diode (LED) over sapphire substrate. Jpn. J. Appl. Phys. 41, L320–L322 (2002).

    ADS  Google Scholar 

  152. Adivarahan, V. et al. High-power deep ultraviolet light-emitting diodes based on a micro-pixel design. Appl. Phys. Lett. 85, 1838–1840 (2004).

    ADS  Google Scholar 

  153. Liu, D. et al. 226 nm AlGaN/AlN UV LEDs using p-type Si for hole injection and UV reflection. Appl. Phys. Lett. 113, 011111 (2018).

    ADS  Google Scholar 

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Acknowledgements

T.-Y.S and H.A. gratefully acknowledge financial support from the National Research Foundation of Korea funded by the Ministry of Science and ICT (Global Research Laboratory programme: NRF-2017K1A1A2013160). M.K. gratefully acknowledges support by the German Research Foundation (DFG) within the Collaborative Research Centre ‘Semiconductor Nanophotonics’ (CRC 787) as well as funding by the Federal Ministry of Education and Research (BMBF) of Germany within the ‘Zwanzig20’ initiative ‘Advanced UV for Life’.

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Authors and Affiliations

  1. Institute of Solid State Physics, Technische Universität Berlin, Berlin, Germany

    Michael Kneissl

  2. Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

    Michael Kneissl

  3. Department of Materials Science and Engineering, Korea University, Seoul, South Korea

    Tae-Yeon Seong

  4. Department of Electrical Engineering, Yale University, New Haven, CT, USA

    Jung Han

  5. Center for Integrated Research of Future Electronics, and Institute of Materials and Systems for Sustainability, Nagoya University, Nagoya, Japan

    Hiroshi Amano

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Kneissl, M., Seong, TY., Han, J. et al. The emergence and prospects of deep-ultraviolet light-emitting diode technologies. Nat. Photonics 13, 233–244 (2019). https://doi.org/10.1038/s41566-019-0359-9

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