Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 2: Nitrides: Devices

HL 2.12: Vortrag

Montag, 1. April 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 Kneissl^1,2 — 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 %.