Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 35: Poster I

HL 35.39: Poster

Dienstag, 8. März 2016, 15:00–19:00, Poster A

Deep UV light emitting diodes with transparent conductive electrodes of multi-layer graphene — •Luca Sulmoni¹, Marc Gluba², Norbert Nickel², Mickael Lapeyrade³, Sven Einfeldt³, Veit Hoffmann³, Johannes Enslin¹, Christian Kuhn¹, Frank Mehnke¹, Tim Wernicke¹, and Michael Kneissl^1,3 — ¹Technische Universität Berlin, Institut für Festkörperphysik, Berlin, Germany — ²Institut für Silizium Photovoltaik, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Berlin, Germany — ³Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany

Light extraction from bottom-emitting ultraviolet (UV) LEDs is challenging, since all metals typically used as p-contacts strongly absorb the light emitted from the active region. In addition, metal contacts directly on p-AlGaN suffer from high p-contact resistances and Schottky type behavior resulting in large operating voltages. This contribution investigates the current injection in AlGaN-based multi-quantum-well UVC LEDs exploiting UV-transparent multi-layer (ML) graphene-based p-electrodes. The p-(Al)GaN/graphene bi-layer exhibit a sheet resistance of 1200, 700 and 400 Ω/square for 1, 2 and 3 ML, respectively. For deep UV LEDs emitting near 265 nm, the excellent lateral current-spreading of the graphene layers and the vertical current injection into the p-n junction are demonstrated with an output power of 1 mW at 70 mA and 21 V. Finally, highly reflective Al/graphene-based p-electrodes on the same UVC LEDs with and without the absorbing p-GaN cap layer will also be presented.