Regensburg 2022 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 20: Poster

DS 20.7: Poster

Mittwoch, 7. September 2022, 16:00–18:00, P3

Tailoring Bonding by Disorder — •Sophia Wahl¹, Yudong Cheng¹, Ricardo Lobo², and Matthias Wuttig¹ — ¹1. Institute of Physics (Ia), RWTH Aachen University, Aachen, Germany — ²LPEM, ESPCI Paris, CNRS, PSL University, Paris, France

The design of material properties and functionalization have been an attractive task for scientists for centuries.

In 1958, Anderson proposed that electronic states in the vicinity close to the Fermi energy will become localised by controlling the degree of disorder. This Anderson localization has been verified in Phase-Change materials like GeSb₂Te₄ (GST). It was shown that depending on the degree of disorder the electrical resistance in GST can be continuously tuned by orders of magnitude without any structural phase transition or stoichiometric changes.

Here, IR spectroscopy and spectroscopic ellipsometry were utilized to investigate the effect of increasing order on the Born effective charge, the dielectric constant є_∞, and the peak value of the imaginary dielectric function є_2,max. Therefore, thin films of GST and GeTe were annealed at various temperatures to change the degree of disorder. Among the decrease of disorder, a change of the optical properties of 20-25% could be achieved while the Born effective charge increased by a factor of 3. This work will give further insight into the opportunity of tailoring solid state properties via disorder and provides a recipe for diverse application including phase change memories, thermoelectrics, and topological insulators.