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

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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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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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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