Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 69: Emerging oxide semiconductors II (Focus session with DS)

HL 69.2: Vortrag

Mittwoch, 2. April 2014, 15:30–15:45, POT 081

Dielectric function of In₂O₃ from the mid-infrared into the vacuum ultraviolet — •Rüdiger Goldhahn¹, Jakob Nixdorf¹, Christian Lidig¹, Klaus Irmscher², Zbigniew Gałazka², Oliver Bierwagen^3,4, James S. Speck⁴, Christoph Cobet⁵, and Martin Feneberg¹ — ¹Institut für Experimentelle Physik, Otto-von-Guericke-Universität Magdeburg — ²Leibniz-Institut für Kristallzüchtung, Berlin — ³Paul Drude Institut für Festkörperelektronik — ⁴University of California, Santa Barbara — ⁵Johannes Kepler Universität, Linz

The optical properties of cubic bixbyite In₂O₃ are under intense discussion. There is not even a consensus about the direct or indirect nature of the fundamental band gap and the corresponding energies. Here, we present spectroscopic ellipsometry from the phonon region in the mid-infrared up to 10 eV using several different instruments including synchrotron radiation. The studies comprise bulk (111) crystals and epitaxial (001) thin films on (001) yttria-stabilized zirconia covering a wide range of electron concentrations (N_s). The dielectric function of In₂O₃ at high energies exhibits pronounced features related to critical points. By analyzing certain peculiarities of ellipsometric data, the fundamental band gap energy to be 2.77 ± 0.02 eV for low N_s. A continuous Burstein-Moss shift is found for increasing N_s. The analysis of the plasma frequency yields an electron effective mass of about 0.23 m₀.