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DS: Fachverband Dünne Schichten
DS 40: Focussed Session: Oxide Semiconductors for Device and Energy Applications I
(Joint session of DS and HL, organized by DS)
DS 40.5: Talk
Thursday, March 10, 2016, 12:00–12:15, H11
Infrared response of cubic In2O3 — •Martin Feneberg1, Christian Lidig1, Jakob Nixdorf1, Oliver Bierwagen2,3, James S. Speck3, Zbigniew Galazka4, and Rüdiger Goldhahn1 — 1Institut für Experimentelle Physik, Otto-von-Guericke Universität Magdeburg — 2Paul Drude Institut für Festkörperelektronik, Berlin — 3Materials Department, University of California, Santa Barbara, USA — 4Leibniz-Institut für Kristallzüchtung, Berlin
The infrared optical response of cubic bixbyite In2O3 samples is investigated in detail. Samples with different concentrations of free electrons from 1.5× 1017 up to 1.6× 1021 cm−3 are measured by spectroscopic ellispometry yielding dielectric functions. Besides transerse optical phonon modes a Drude contribution accounting for the free electron gas is observed and analyzed.
The broadening factor in the Drude contribution can be understood as characteristic relaxation time constant. Its frequency dependency is visible in point-by-point fitted dielectric functions, i.e. without assumptions about the line shape. The broadening factor is found to be a constant within errors of measurement.
By comparison with Hall-effect data, the effective electron mass is found to be a function of energy increasing from m* =0.18m0 at the Γ-point of the Brillouin zone. This is direct proof of the non-parabolic nature of the conduction band.