DFG- FG 957: Polarcon: Kontrolle der Polarisationsfelder in GaN basierten Lichtemittern: Mikroskopische Korrelation der elektronischen und optischen Eigenschaften mit der kristallinen Realstruktur von Polarisations-Feld-kontrollierten Gruppe-III-Nitriden

For a detailed understanding of complex semiconductor heterostructures and the physics of devices based on them, a systematic determination and correlation of the structural, chemical, electronic, and optical properties on a micro- or nano-scale is mandatory. Luminescence techniques belong to the most sensitive, non-destructive methods of semiconductor research, and the combination of time-resolved luminescence spectroscopy with the high spatial resolution of a scanning electron microscope, as realized by the technique of cathodoluminescence microscopy, provides a powerful tool for the optical nano-characterization of semiconductors, their heterostructures as well as their interfaces. As part of the research group proposal “Polarization field control in nitride light emitters” we shall correlate the electronic and optical properties of non- and semipolar epitaxial nitride structures on a micro- and nano-scale with the crystalline real structure. Morphological defects like dislocations and – in particular in non-c-axis grown material – stacking faults and spontaneous and piezo-electric polarization fields are the major problems in group-III-nitrides. In ternary and quaternary alloys as well as in their hetero-structures nano-scale fluctuations of stoichiometry and/or interfaces have strong impact on the radiative recombination in light emitters. In close collaboration with the growth projects (UUlm, TUBs, OvG-D, and TUB) and perfectly complementing the experimental techniques by exchange with the TEM, µPL, and µEL project (URgb), we will address these problems.