Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 22: Focused Session: Semi- and nonpolar group III nitrides II

HL 22.3: Topical Talk

Dienstag, 24. März 2009, 15:00–15:30, BEY 118

Microscopic Correlation of Structural, Electronical and Optical Properties of semi- and non-polar grown Group-III-Nitrides — •Frank Bertram — Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg, Germany

Although tremendous progress has been achieved in the growth of GaN, there are still many fundamental problems remaining: In particular reaching higher quantum efficiency and extending the spectral range towards shorter and longer wavelengths. One principal physical problem is the quantum confined Stark effect as a consequence of the strong internal electrical polarization fields in c-direction. The most common strategy to overcome the QCSE-problem is to avoid or minimize the polarization fields by growing the heterostructures in other directions, e.g. perpendicular to the GaN c axis by using a- or m-plane nitrides. Another approach to reduce the fields is growing in semi-polar directions. However, epitaxial growth on such planes is by far less developed than the growth on the commonly used c-plane. 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. We correlate the structural, electronical and optical properties of non- and semipolar epitaxial nitride structures on a micro- and nano-scale with the crystalline real structure using spatially/spectrally/time-resolved cathodoluminescence.