Dresden 2009 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 2: GaN: devices
HL 2.4: Vortrag
Montag, 23. März 2009, 11:00–11:15, BEY 118
Towards InGaN-based light emitters with superior high-current performance — •Ansgar Laubsch1, Matthias Sabathil1, Werner Bergbauer1, Martin Strassburg1, Matthias Peter1, Hans Lugauer1, Tobias Meyer1, Joachim Wagner2, Norbert Linder1, Klaus Streubel1, and Berthold Hahn1 — 1OSRAM Opto Semiconductors GmbH, Leibnizstrasse 4, 93055 Regensburg, Germany — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Tullastrasse 72, 79108 Freiburg, Germany
The last decade has seen tremendous progress in the epitaxial growth and in advanced chip designs of light emitting diodes (LEDs) with InGaN/GaN quantum-well (QW) heterostructures. This recently enabled an efficiency for conversion of electrical to optical power of almost 60 % for a blue ThinGaN® LED at operation current. Still, the internal quantum efficiency of such devices peaks far below the operation current density and then decreases monotonously. Understanding of this mechanism is crucial to reach the ultimate limits in efficiency. We identify a QW internal high density Auger-like loss process as the culprit and model our data with a coefficient of C = 3.5 · 10−31 cm−6s−1. Thick InGaN QWs and an optimized multi quantum well structure are ways to reduce the carrier density. We study the physics of recombination and carrier distribution in such structures. Consistent with simulations, both concepts exhibit reduced high current saturation. We thus conclude that regardless of the employed concept, a decrease in carrier density is central to improve the high current efficiency of InGaN based light emitters.