Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 81: Focus Session: Extended defects in semi- and nonpolar GaN II
HL 81.5: Vortrag
Donnerstag, 14. März 2013, 16:00–16:15, H13
Defects of polar, semipolar and nonpolar (In)GaN - a comparison — •Lukas Schade1,2, Tim Wernicke3, Kamran Forghani4,5, Jens Raß3, Simon Ploch3, Lutz Kirste2, Markus Weyers6, Michael Kneissl3,6, Ferdinand Scholz4, and Ulrich Schwarz1,2 — 1Department of Microsys tems Engeneering, IMTEK, University Freiburg — 2Fraunhofer Institute for Applied Solid State Physics — 3Institute of Solid State Physics, Technical University Berlin — 4Institute for Optoelectronics, University Ulm — 5University of Wisconsin, Madison, USA — 6Ferdinand-Braun-Institute, Berlin
The GaN/InGaN material system is used to realize light emitting diodes from UV-A to the green-yellow spectral region. However, even on quasi bulk GaN substrates threading dislocations (TDs) are present with a density of 107 cm−2. Here, we examine the influence of TDs on the luminescence intensity and transition energy. The impact caused by nonradiative recombination centers and strain fields is analyzed by micro photoluminescence and white light interferometry. We compare TDs in differently oriented GaN layers and InGaN QWs. Three types of burgers vectors are typically observed in GaN: a, c and a+c. When the surface orientation is changed from (0001) c-plane to (1010) m-plane, their character changes from edge to screw type and vice versa. We studied TDs and V-defects associated to them in polar, semipolar and nonpolar GaN and InGaN QWs. Additionally, we will present the effect of Si doping onto the strain field in (0001) GaN edge dislocations. In undoped GaN, the strain around such a dislocation forms a symmetric dipole. With Si doping, the strain dipole becomes asymmetric.