Berlin 2018 – wissenschaftliches Programm
DS 3.10: Vortrag
Montag, 12. März 2018, 12:00–12:15, E 020
Characterization of the dielectric function of RScO3 type scandates — •Sergey Kuznetsov1,2, 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.