Project A1:

From structure – property correlations to tailor-made chalcogenides
(since 2015)

Understanding phase-change materials (PCMs) on the atomic scale is the first and most fundamental step towards better memory devices – one hopes to improve existing materials or even design new ones from scratch. In this project, we merge first-principles modelling and careful experiments to achieve a microscopic understanding of complex chalcogenides. In particular, we are interested in how charge transport through crystalline PCMs can be tailored by the interplay of stoichiometric modifications and self-doping. Furthermore, we will extend our scope from crystalline to amorphous PCMs ("zero bits"); in the long term, we aim to understand and control the chemical nature in both.

Structure – property relationship for chalcogenides:
The role of chemical bonding and defects
(2011 - 2015)

Phase-change materials are characterized by a unique property portfolio which includes a pronounced change of optical properties upon crystallization of the amorphous state. This finding is a unique identifier for this class of materials. Recently this observation has been attributed to the "resonance bonding" description of covalency in crystals. We intend to derive a microscopic understanding of the chemical bonding and how its strength depends upon the composition and atomic arrangement of the crystalline phase. We are investigating the electronic structure of phase change materials both theoretically and experimentally and will relate it to the material composition with the ultimate goal to design phase change materials by choosing materials with suitable composition which feature resonance bonding. Particular emphasis is devoted to understand the nature of defects and their influence on material properties.

Principal investigators:

Prof. Dr. rer. nat. R. Dronskowski
Institute für Anorganische Chemie
RWTH Aachen University
Phone: +49 (0)241 80 93642

Prof. Dr. rer. nat. M. Wuttig
I. Physikalisches Institut IA
RWTH Aachen University
Phone: +49 (0)241 80 27155

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