Berlin 2018 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 27: Nitrides: Preparation and characterization II

HL 27.10: Talk

Wednesday, March 14, 2018, 12:00–12:15, EW 203

Parametric model for the anisotropic dielectric function of m-plane AlGaN up to 20eV — •Michael Winkler¹, Martin Feneberg¹, Shigefusa F. Chichibu², Ramón Collazo³, Zlatko Sitar³, Maciej D. Neumann⁴, Norbert Esser⁴, and Rüdiger Goldhahn¹ — ¹Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg, Germany — ²Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Japan — ³Department of Materials Science and Engineering, North Carolina State University, USA — ⁴Leibniz-Institut für Analytische Wissenschaften - ISAS, Berlin, Germany

The linear optical response of nonpolar (1010) (m-plane) Al_xGa_1−xN epitaxial films was analyzed quantitatively for the full composition range. The samples were grown by metal-organic vapor phase epitaxy and molecular beam epitaxy on m-plane freestanding GaN and AlN substrates. Spectroscopic ellipsometry up to 20eV was measured at the synchrotron Metrology Light Source (MLS) of the PTB in Berlin for each sample. Using a point-by-point fit the ordinary and the extraordinary dielectric functions were obtained.

These data were used to fit the parameters for an ordinary and extraordinary model DF ε_⊥,∥(x,ω) in the spectral range from 0.7eV to 20eV, where the AlN-concentration x can be chosen arbitrarily. The model DF compares well with previous results for the ordinary DF and with the position of the high energy interband transitions.