Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 50: Nitrides: Preparation and Characterization

HL 50.10: Vortrag

Mittwoch, 22. März 2017, 12:30–12:45, POT 251

Anisotropic dielectric function of nonpolar AlGaN up to 20eV — •Michael Winkler¹, Shigefusa F. Chichibu², Ramon Collazo³, Zlatko Sitar³, Maciej D. Neumann⁴, Norbert Esser⁴, Rüdiger Goldhahn¹, and Martin Feneberg¹ — ¹Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg — ²Institute of Multidisciplinary Research for Advanced Materials, Tohoku University — ³Department of Materials Science and Engineering, North Carolina State University — ⁴Leibniz-Institut für Analytische Wissenschaften - ISAS

The linear optical response of nonpolar (1010) Al_xGa_1−xN epitaxial films is 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. Their optical properties were measured by spectroscopic ellipsometry up to 20eV performed at the synchrotron Metrology Light Source (MLS) of the PTB in Berlin for two different configurations: One with the [0001]-direction parallel and one perpendicular to the plane of incidence. By modeling the multilayer samples including surface roughness and anisotropy the ordinary and extraordinary dielectric functions were obtained. High energy interband transitions are thus traceable as function of x in the Al_xGa_1−xN system allowing assignments of features to certain parts of the band structure.