Parts | Days | Selection | Search | Updates | Downloads | Help
HL: Fachverband Halbleiterphysik
HL 35: Poster I
HL 35.39: Poster
Tuesday, March 8, 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 Kneissl1,3 — 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.