Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 65: GaN-based Devices

HL 65.4: Talk

Friday, March 26, 2010, 11:00–11:15, H15

Heterostructure design optimisation of (In)AlGaN deep ultraviolet light emitting diodes — •T. Kolbe¹, T. Sembdner¹, A. Knauer², V. Küller², H. Rodriguez², 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 (UV) light emitting diodes (LEDs) based on III-nitride semiconductors have attracted great interest in recent years. However, due to weak carrier confinement, strong piezoelectric fields and high defect densities the external quantum efficiency of UV LEDs is still only a few percent.
We have investigated 316 nm (In)AlGaN LEDs with one, three, five and seven quantum wells (QWs). The carrier injection in the devices is simulated and compared to electroluminescence measurements. The emission power of all devices is nearly the same due to a strongly inhomogeneous carrier distribution between the wells. In the secound series (In)AlGaN multi-quantum-well UV LEDs with a varying QW thickness of 1.5 nm, 2.2 nm and 3.2 nm have been investigated. We could show that the light output power depends strongly on the QW thickness. The highest output power was obtained for the LEDs with a QW thickness of 2.2 nm. This effect is attributed to the interplay between electron and hole wave function overlap and carrier concentration in the active region.