SKM 2021 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 3: Poster Session I
HL 3.10: Poster
Monday, September 27, 2021, 10:00–13:00, P
Terahertz spectroscopy on nanograined Bismuth Telluride pellets — •Ahana Bhattacharya1, Jeongwoo Han1, Sepideh Izadi3,4, Sarah Salloum2, Stephan Schulz2, Gabi Schierning3, and Martin Mittendorff1 — 1Department of Physics, University of Duisburg-Essen,47057, Duisburg, Germany — 2Department of Chemistry, University of Duisburg-Essen, 45141, Essen, Germany — 3Department of Physics, Experimental Physics, Bielefeld University, 33615, Bielefeld, Germany — 4Leibniz IFW Dresden, Institute for Metallic Materials, 01069, Dresden, Germany
Topological insulators (TI) host surface carriers with a very high mobility. However, the transport properties of extended crystals are dominated by bulk carriers which outnumber the surface carriers by orders of magnitude. One way to overcome the domination of bulk carriers is to use compacted TI nanoparticles. Bismuth Telluride nanoparticles which are compacted by hot pressing to nanograined bulk samples with a high surface to volume ratio are studied and analyzed.
THz time-domain spectroscopy is used as a tool to elucidate the contribution of surface and bulk carriers to the transport properties. While this is not possible with dc measurements, this can be achieved by measuring the reflection as a function of the frequency. Charge carriers with a high mobility lead to a pronounced frequency dependence of the conductivity, and thus the reflection, while low mobility carriers lead to a rather flat response. Analyzing the experimental results at various temperatures allows us to understand the role of surface and bulk carriers