Dresden 2014 – scientific programme

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DS: Fachverband Dünne Schichten

DS 40: Focus Session: Resistive Switching by Redox and Phase Change Phenomena VII (Optical properties and theory of PC materials)

DS 40.1: Talk

Thursday, April 3, 2014, 11:30–11:45, CHE 89

Near-field optical investigation of Sb₂Te₃ hexagonal platelets in the mid-infrared — Benedikt Hauer¹, Tobias Saltzmann², Ulrich Simon², and •Thomas Taubner¹ — ¹Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany — ²Institute of Inorganic Chemistry (IAC), RWTH Aachen University, 52056 Aachen, Germany

Antimony telluride (Sb₂Te₃) has gained attention as a candidate for phase-change memory applications, thermoelectric devices, and as a three-dimensional topological insulator. We imaged Sb₂Te₃ hexagonal platelets grown by hydrothermal synthesis using scattering-type scanning near-field optical microscopy (s-SNOM).

In the mid-infrared spectral range between 5.5 µm and 11 µm we find a highly symmetric and very sharp pattern in both optical amplitude and phase images. This optical pattern is correlated to a growth spiral and extends over the entire platelet. We assume domains with different surface-densities of charge carriers to be the origin of the optical contrast. These domains could be caused by growth twins in the crystal lattice. On epitactically grown Sb₂Te₃ samples we did not observe any comparable pattern.

This contribution demonstrates the unique potential of s-SNOM to visualize fundamental material properties that are hard to address with any other method.