Dresden 2009 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.28: Poster

Monday, March 23, 2009, 14:30–17:00, P2

TEM Investigation of Ultrathin GaInN/GaNQuantum Well Structures with high Indium Content — •Lars Hoffmann, Heiko Bremers, Holger Jönen, Daniel Dräger, 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. Therefore, a green laser diode based on GaN still has to be demonstrated. Material quality and very high piezoelectric fields are the likely cause for that. 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. Some of the grown structures showed partial relaxation and thermal degradation. Moreover, we observed high defect densities in the low temperature grown upper waveguides. We investigate the mechanisms of relaxation and possible misfit dislocation generation in the QW structures.