Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 3: Oxide Semiconductors for Novel Devices (Focussed Session): Session I

DS 3.10: Talk

Monday, March 12, 2018, 12:00–12:15, E 020

Characterization of the dielectric function of RScO₃ type scandates — •Sergey Kuznetsov^1,2, Martin Feneberg¹, and Rüdiger Goldhahn¹ — ¹Institute of Experimental Physics, Otto-von-Guericke University Magdeburg, Germany — ²Drexel University Department of Physics, Philadelphia, USA

Due to their high energy band gap and their structural stability towards temperature differences, wide-gap Perovskite structured oxides of type RScO₃ are promising candidates for replacing SiO₂ as high-k gate dielectrics. These Sc-based crystals are also among best available bulk substrates for the epitaxial growth of high-quality ferroelectric thin films, however, only limited data on their optical properties is available. Here, we present the results of spectroscopic ellipsometry from the infrared (0.04eV) up to the ultraviolet (6.6eV) at room temperature on SmScO₃, GdScO₃, TbScO₃, and DyScO₃ bulk single-crystals. The purpose of the experiments was to determine the in-plane components of the real and imaginary dielectric functions (DF). The analysis revealed 4 phonon modes in the extraordinary DF, and 8 to 9 modes in the ordinary DF. The phonon frequencies are observed to shift systematically with the atomic mass of the rare earth component of the perovskites. This effect was observed in the ordinary and extraordinary DF. Data obtained also indicate the onset of interband absorption at 6 ± 0.1 eV for GdScO₃ and DyScO₃, and at 5 ± 0.1 eV in the SmScO₃ and TbScO₃, with a local maximum at 5.4 eV prior to exhibiting similar behavior to the other two samples. A comprehensive overview of the anisotropic dielectric functions will be shown.