Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Poster: Nitrides

HL 31.5: Poster

Montag, 31. März 2014, 17:00–20:00, P2

Optical investigations of exciton-phonon coupling in GaInN quantum wells — •Manuela Klisch, Fedor Alexej Ketzer, Torsten Langer, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Institut für Angewandte Physik, TU Braunschweig

The photoluminescence of GaInN quantum wells shows asymmetric luminescence spectra, which can be consistently explained via sidebands due to coupling of excitons with longitudinal optical phonons (LO-phonons) and due to Fabry-Perot interferences. Therefore we investigate different GaInN quantum well structures grown via low pressure MOVPE by continuous wave photoluminescence. The Huang-Rhys factor, which describes the coupling strength between electron-hole pairs and LO-phonons, is determined by a fit considering Fabry-Perot interferences and up to three LO-phonon sidebands. To determine the origin of the strong coupling between LO-phonons and the recombining electron-hole pairs we change several parameters. The Huang-Rhys factor is analysed as a function of temperature, well width and indium content. We observe that the Huang-Rhys factor increases with the well width and indium content. For this effect we provide an explanation that compares excitons to donor-acceptor pairs considering the Huang-Rhys factor. We observe a thermally activated behavior of the Huang-Rhys factor. At temperatures below 120 K, this behavior is consistent with a thermalization of excitons and the S-shaped temperature dependence of the emission energy. Towards higher temperature, monotonously increasing Huang-Rhys factors are observed likely due to contributions of excitonic 2s states.