Regensburg 2019 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 2: Nitrides: Devices
HL 2.12: Talk
Monday, April 1, 2019, 12:30–12:45, H31
Influence of the GaN:Mg contact layer on the performance characteristics of AlGaN based UVC LED heterostructures — •Eviathar Ziffer1, Norman Susilo1, Luca Sulmoni1, Martin Guttmann1, Tim Wernicke1, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics, Berlin, Germany — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Berlin, Germany
AlGaN based UVC LEDs emitting at 265 nm are typically capped with a thick GaN:Mg contact layer in order to achieve low resistivity, ohmic p-contacts. However, the GaN:Mg layer strongly absorbs the UVC light emitted into the p-side of the LED, thereby limiting its light extraction efficiency. In this study, we investigate the performance of UVC LEDs with different GaN:Mg layer thicknesses ranging from 5 nm to 160 nm. The heterostructures were grown by metalorganic vapor phase epitaxy and fabricated into LEDs by standard micro-fabrication techniques with highly reflective p-contacts and vanadium-based n-contacts. For thin GaN:Mg layers, an increasing operation voltage and a reduced yield of working LEDs were observed. At the same time, the on-wafer external quantum efficiency drastically increases with decreasing GaN:Mg cap thickness from 0.6 % to 2.1 %.