Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 45: GaN devices
HL 45.9: Vortrag
Donnerstag, 28. Februar 2008, 11:30–11:45, EW 202
Enabling factors for the improvement of nitride-based LED efficiency — •Ansgar Laubsch1, Werner Bergbauer1, Matthias Sabathil1, Matthias Peter1, Tobias Meyer1, Georg Brüderl1, Joachim Wagner2, Norbert Linder1, Klaus Streubel1, Raimund Oberschmid1, and Berthold Hahn1 — 1OSRAM Opto Semiconductors GmbH, Regensburg, Germany — 2Fraunhofer-Institut für Angewandte Festkörperphysik, Freiburg, Germany
Recent progress in the epitaxial growth of LEDs with InGaN/GaN quantum-well heterostructures has led to a significant enhancement of output power. In this talk, we will discuss the mechanisms limiting the devices' internal efficiency and identify enabling factors for further improvements. We compare samples with different Indium content as well as different design of the active layer.
Although heteroepitaxial growth of GaN on sapphire generates high defect densities, non-radiative defect-related Shockley-Read-Hall recombination does not seem to substantially limit the efficiency of standard InGaN/GaN LED structures. We rather discuss a supplemental Auger-like non-radiative path for carrier recombination that becomes dominant at quantum-well carrier densities typical for LED operation. Additionally, the piezo-field induced reduced overlap of electron and hole wavefunction in standard c-plane grown InGaN quantum wells reduces the radiative recombination rate.