Regensburg 2007 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 46: Poster 2
HL 46.11: Poster
Thursday, March 29, 2007, 15:00–17:30, Poster A
Infrared Ellipsometry of cubic and hexagonal InN — •Christian Napierala1, Pascal Schley1, Rüdiger Goldhahn1, Gerhard Gobsch1, Jörg Schörmann2, Donat J. As2, Klaus Lischka2, Martin Feneberg3, and Klaus Thonke3 — 1Institut für Physik, TU Ilmenau — 2Department Physics, Universität Paderborn — 3Institut für Halbleiterphysik, Universität Ulm
Recent experimental studies revealed for both, hexagonal and cubic InN, a band gap below 0.7 eV. Despite the progress in growth, the epitaxial layers suffer from the still high electron density. Under those conditions, the non-parabolicity of the conduction band becomes important when the absorption properties around the gap are discussed or the plasmon excitations in the phonon range are analysed. Using ellipsometry and reflectance measurements we have determined the dielectric function (DF) of the InN polytypes for the two spectral regions. Compared to previous studies a refined analysis of the DF shape is presented. In particular we show how the non-parabolicity influences the plasma frequency and thus the phonon-plasmon coupling. It is demonstrated in addition that the high-frequency dielectric constant is in fact not constant, but depends on the carrier-induced Burstein-Moss shift of the absorption edge.