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HL: Fachverband Halbleiterphysik

HL 2: GaN: devices

HL 2.5: Vortrag

Montag, 23. März 2009, 11:30–11:45, BEY 118

Heterostructure design optimisation of deep (In)AlGaN ultraviolet light emitting diodes — •T. Sembdner¹, T. Kolbe¹, A. Knauer², V. Küller², S. Einfeldt², P. Vogt¹, M. Weyers², and M. Kneissl^1,2 — ¹TU Berlin, Institute of Solid State Physics, Hardenbergstr. 36, 10623 Berlin, Germany — ²Ferdinand-Braun-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin, Germany

Ultraviolet light emitting diodes (LEDs) based on III-nitride semiconductors have attracted great interest in recent years. However, due to week carrier confinement, strong piezoelectric fields and high defect densities the external quantum efficiencie of ultraviolet LEDs is still in the lower percent range.
Here we present a comparison of heterostructure design simulations and experimental results for deep ultaviolet (In)AlGaN-multiple quantum well (MQW) LEDs grown by metalorganic vapour phase epitaxy on (0001) sapphire substrates. The emission wavelength was found near 320nm for an active region comprised of (In)AlGaN quantum wells and (In)AlGaN barrier layers. For these structures the effects of the p-contact layer design, the electron blocking layer and the MQW active region on the external quantum efficiency is investigated. The latter influence is particularly important as our simulations have shown that a single quantum well LED has a higher radiative rekombination rate in comparison with a MQW LED.