Enhanced Wall Plug Efficiency of AlGaN-Based Deep-UV LEDs Using Mo/Al as p-Contact

H.K. Cho1, N. Susilo2, M. Guttmann2, J. Rass1, I. Ostermay1, S. Hagedorn1, E. Ziffer2, T. Wernicke2, S. Einfeldt1, M. Weyers1, and M. Kneissl1,2

Published in:

IEEE Photonics Technol. Lett., vol. 32, no. 14, pp. 891-894 (2020).

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P-type contacts with a high reflectivity in the ultra-violet spectral region made of molybdenum/aluminum (Mo/Al) on AlGaN-based deep-ultraviolet light-emitting diodes (DUVLEDs) emitting at 265 nm have been investigated. Optimized Mo/Al contacts are shown to have a high optical reflectivity above 75% at 265 nm. DUV LEDs with an absorbing p-AlGa heterostructure operated at 20 mA show a 15% higher light output power and a 1 V lower voltage when Mo/Al instead of Pt is used as p-contact. The effect on the voltage of DUV LEDs with a UV-transparent p-side heterostructure is similar. Moreover, DUV LEDs with a Mo/Al contact show a lower operation voltage compared to LEDs with an indium tin oxide/aluminum (ITO/Al) p-contact where the ITO is intended to form a semitransparent low-resistance contact and the Al serves as a reflector.

1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
2 Institute of Solid State Physics, Technical University of Berlin, 10623 Berlin, Germany

Index Terms:

Deep UV, light emitting diodes (LEDs), p-AlGaN, reflective p-side contact, efficiency.