Regensburg 2019 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 31: Nitrides: Preparation and characterization II
HL 31.6: Vortrag
Mittwoch, 3. April 2019, 16:30–16:45, H31
Optical properties of nonpolar GaN/AlN superlattice structures — •Michael Winkler1, Hagen Brähmer1, Martin Feneberg1, Norbert Esser2, Eva Monroy3, and Rüdiger Goldhahn1 — 1Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Germany — 2Leibniz-Institut für Analytische Wissenschaften - ISAS, Berlin, Germany — 3University Grenoble-Alpes, CEA, Grenoble, France
Semiconductor superlattice structure are used in optoelectronic devices as active material, for strain management or are parts of waveguides. The dielectric losses in this multilayer structures have a significant impact on efficiency of such devices.
The anisotropic optical properties of (1100) oriented gallium-nitride/aluminium-nitride superlattice structures were studied by synchrotron-based spectroscopic ellipsometry for photon energies up to 10eV. The samples were grown by plasma-assisted molecular-beam epitaxy. Samples with period length of 5.1nm, 5.9nm, and 6.7nm were studied.
Both, a multilayer and an effective layer approach were used to model the experimental data. From the latter, ordinary and extraordinary dielectric functions were deduced by fitting wavelength-by-wavelength. We compare the obtained DFs with results from the multilayer approach, photoluminescence data, and calculated interband transitions. The effects of the non-parabolic valence bands and the limits for the effective layer approach will be discussed in detail.