Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 98: Nitrides: Bulk material, films, surfaces and quantum wells

HL 98.1: Talk

Friday, March 20, 2015, 09:30–09:45, EW 201

Valence band tomography in wurtzite GaN — •Martin Feneberg, Karsten Lange, Michael Winkler, Matthias Wieneke, Hartmut Witte, Jürgen Bläsing, Armin Dadgar, and Rüdiger Goldhahn — Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg

Effective masses describe the curvature of the conduction and valence bands. These masses are extremely important input parameters for device design, understanding optical or transport phenomena, and evaluating theoretical results. However, especially the hole masses are experimentally largely unexplored.

Here, we present valence band tomography performed by analyzing spectroscopic ellipsometry data of a-plane wurtzite GaN with free electron concentrations up to 10²⁰ cm⁻³. The conduction band curvature of the same set of samples is already known from infrared studies [1]. By taking into account Burstein-Moss shift and band gap renormalization, the onset of the anisotropic interband absorption reveals the valence band edges for k>0 in certain directions. This analysis yields the valence band curvature for the upper two valence bands.

[1] M. Feneberg, K. Lange, C. Lidig, M. Wieneke, H. Witte, J. Bläsing, A. Dadgar, A. Krost, and R. Goldhahn, Appl. Phys. Lett. 103, 232104 (2013).