Highly Reflective p-Contacts Made of Pd-Al on Deep Ultraviolet Light-Emitting Diodes
H.K. Cho1, I. Ostermay1, U. Zeimer1, J. Enslin2, T. Wernicke2, S. Einfeldt1, M. Weyers1, and M. Kneissl1,2
Published in:
IEEE Photonics Technol. Lett., vol. 29, no. 24, pp. 2222-2225 (2017).
Abstract:
Highly reflective metal contacts for the p-layers of AlGaN-based deep ultraviolet light emitting diodes (DUV LEDs) emitting at 305 nm have been investigated. Different Pd-Al metal stacks have been examined and a reflectivity of 82% was obtained after annealing, which is about two times the value measured for conventional Pd contacts. The high reflectivity is attributed to the formation of an Al4Pd phase besides an Al phase in the annealed contact. DUV LEDs with highly-reflective Pd-Al contacts exhibited an increase of the light output power by 30% at a dc current of 20 mA.
1 Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, 12489 Berlin, Germany
2 Institute of Solid State Physics, Technische Universität Berlin, 10623 Berlin, Germany
Index Terms:
Deep UV, light emitting diodes (LEDs), AlGaN, reflective ohmic contact.
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