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DS: Fachverband Dünne Schichten
DS 20: Poster II
DS 20.35: Poster
Thursday, March 21, 2024, 18:00–20:30, Poster D
Optical Analysis of Sputtered (IST)1−x(SnTe)x Thin Films — •Thomas Schmidt1, Christian Stenz1, Michael Dappen1, and Matthias Wuttig1,2 — 11. Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany — 2JARA Institute Green IT (PGI-10), Forschungszentrum Jülich, 52428 Jülich, Germany
Phase-change materials (PCMs) are characterized by a strong contrast in optical properties between amorphous and crystalline phases. Unlike other PCMs, crystalline In3SbTe2 (IST) shows metallic behavior. Therefore, IST arouses interest in nanophotonic applications. However, the optical property contrast is mainly limited to the infrared spectrum. Alloying IST with other compounds is an attempt to expand the optical contrast to the visible spectrum. One of those alloy-candidates is SnTe, which is characterized by a negative real part of the dielectric function є=є1+i·є2, a high maximum value of є2 at around 2.2 eV and the same rocksalt-like structure in the crystalline phase as IST. Metavalently bonded (MVB) materials, like SnTe, are characterized by significantly different properties compared with compounds employing one of the fundamental well-established bonding mechanisms (e.g. ionic, metallic, covalent). In order to link optical properties with chemical bonding, spectroscopic ellipsometry and Fourier transform infrared spectroscopy (FTIR) was performed on sputtered thin films of approx. 75 nm thick (IST)1−x(SnTe)x. From this, the dielectric function of the amorphous and crystalline samples can be extracted. The changes in the dielectric function є of the crystalline phase can be assigned to a transition of chemical bonding from metallic to MVB.
Keywords: Phase-Change Materials; Dielectric Function; In-Sb-Te; SnTe; Sputter Deposition