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HL: Fachverband Halbleiterphysik

HL 34: Poster I: III-V Semiconductors

HL 34.38: Poster

Dienstag, 23. März 2010, 18:30–20:30, Poster D2

TEM Investigation of c- and m-plane GaInN/GaN Quantum Well Structures with high Indium Content — •Lars Hoffmann, Heiko Bremers, Holger Jönen, Uwe Rossow, and Andreas Hangleiter — TU Braunschweig, Institute of Applied Physics, Braunschweig, Germany

While GaN-based blue light emitting diodes exhibit exceptionally large internal quantum efficiencies (up to 80% at room temperature) their green counterparts quickly become less efficient at longer wavelength. A green laser diode based on c-plane GaN has been demonstrated, but the origin of the green gap is still far from being understood. While LED efficiency greatly benefits from V-shaped pits decorating threading dislocations, laser diodes require highly perfect interfaces and homogeneous quantum wells. Using Transmission Electron Microscopy (TEM) we have studied ultrathin (< 2nm) high indium content quantum well (QW) structures suitable for blue-green laser diodes. We investigate the mechanisms of relaxation and possible misfit dislocation generation in c- and m-plane QW structures, partial relaxation and thermal degradation. Moreover, we investigate the appearance of defects in the low temperature grown upper waveguides.