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HL: Fachverband Halbleiterphysik

HL 85: Poster Session II

HL 85.122: Poster

Donnerstag, 17. März 2011, 18:00–21:00, P4

Scanning near-field optical microscopy on UV emitting GaN/AlGaN quantum well structures — •Peter Clodius, Holger Jönen, Uwe Rossow, and Andreas Hangleiter — Technische Universität Braunschweig, Institut für Angewandte Physik, Mendelssohnstr. 2, 30106 Braunschweig

The efficiency of GaN/AlGaN quantum well (QW) structures is quite low compared to GaInN/GaN structures emitting in the blue/violet spectral region which show very high efficiencies despite the high defect density that is commonly observed in such structures. Our explanation for the high efficiency of GaInN/GaN structures is based on the observation that every dislocation in highly efficient c-plane GaInN/GaN structures is decorated with a so-called V-pit, a hexagonal shaped inverted pyramid with (1011) sidewalls. On these sidewalls, thinner quantum wells act as a barrier, suppressing nonradiative recombination at the defects. TEM measurements on high efficiency GaN/AlGaN UV structures have shown that pit formation around defects also takes place in those structures [1]. In this contribution, we will present scanning near-field optical microscope (SNOM) measurements of the luminescence of these high efficiency UV emitting GaN/AlGaN quantum well structures with a spatial resolution below 100 nm. Light emission with a wavelength shorter than that of the c-plane QW, originating from the sidewalls of the pits, which is visible in low temperature measurements, indicates that a similar mechanism is present in UV structures.

[1]D. Fuhrmann et. al. Phys. Rev. B 79, 073303 (2009)