Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 27: GaN: preparation and characterization I
HL 27.4: Vortrag
Mittwoch, 25. März 2009, 10:15–10:30, BEY 81
Electro-optical properties of InGaN-based LED structures on the sub-µm length scale — •Clemens Vierheilig1, Ulrich T. Schwarz1, Nikolaus Gmeinwieser2, Ansgar Laubsch2, and Berthold Hahn2 — 1Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany — 2OSRAM Opto Semiconductors GmbH, Leibnizstraße 4, 93055 Regensburg, Germany
The optical properties of InGaN-based quantum wells show strong fluctuations on different length scales. With pure optical measurements of the photoluminescence signal of the quantum wells it is not possible to separate effects of fluctuations of the quantum well width or indium content from local nonradiative recombination of the excited charge carriers. For this reason, we perform photoluminescence measurements with high spatial resolution (µPL) under external bias in combination with measurements of the laser beam induced photocurrent (LBIC). The strong fluctuations of the PL intensity on a length scale of several µm are also observed in the spectral position of the quantum well and the LBIC under reverse external bias. This indicates fluctuations of the quantum well width. An additional strong intensity fluctuation of the PL intensity on the sub-µm length scale is not observed in the LBIC signal. These short-range fluctuations are interpreted in terms of local nonradiative recombination.