Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 27: GaN: preparation and characterization I

HL 27.1: Vortrag

Mittwoch, 25. März 2009, 09:30–09:45, BEY 81

SNOM measurements of GaInN/GaN and GaN/AlGaN light emittting quantum well structures — •Peter Clodius, Holger Jönen, Lars Hoffmann, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Technische Universität Braunschweig, Institut für Angewandte Physik, Braunschweig

Today Group-III-Nitride based light emitting quantum well (QW) structures are used in a wide range of applications, from near green to blue and (ultra)violet LEDs and LDs. The high efficiency of the GaInN/GaN-QW structures in the blue and violet region is still a matter of discussion. Our explanation is based on the fact that, in high efficiency structures, nearly every dislocation in growth direction for c-plane surfaces, is decorated by a so called V-pit (hexagonal V-shaped structures with (1011) sidewalls). On these sidewalls the growth rate of the QWs is reduced, compared to the growth on c-plane, which leads to thinner QWs with an increased bandgap, causing a potential which prevents charge carriers from reaching possible centers of non-radiative recombination at these defects. Recent SNOM-measurements showed a high energy emission from areas surrounding these pits even at room temperature. In this talk we will present the results of further experiments, trying to clarify the origin of this unusual emission. We will also present first measurements of GaN/AlGaN based QW structures emitting in the ultraviolet, investigating if V-pits play a role in these structures as well.