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MM: Fachverband Metall- und Materialphysik

MM 42: Materials for Energy Storage and Conversion - Functional Materials

MM 42.2: Vortrag

Mittwoch, 18. März 2020, 16:00–16:15, IFW D

Defect Calculations to Explain Charge-Carrier Transition in Disordered Chalcogenides — •Valentin Evang¹, Johannes Reindl², Alexander Rochotzki², Matthias Wuttig^2,3, and Riccardo Mazzarello^1,3 — ¹Institute for Theoretical Solid State Physics, RWTH Aachen University, 52056 Aachen — ²I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen — ³JARA-FIT, RWTH Aachen University, 52056 Aachen

Phase-change materials (PCMs) like GeSbTe and other chalcogenides promise to be key ingredients for future non-volatile memory thanks to their remarkable dynamic properties when switched between their crystalline and amorphous phases. Furthermore, they show features in atomic bonding, recently coined metavalent, that are incompatible with the well-known bonding types and could play an important role in the design of materials with specific phase-change properties.

For a related material, the disordered cubic phase of PbSbTe, experiments reveal a transition from n-type to p-type conduction as a response to annealing at high temperatures. During this process, only subtle changes in the crystal structure take place, pointing towards varying types of self-doping to cause the transition.

Here, we employ density functional theory to compute the formation energies of various possible defects in the disordered cubic and related phases of PbSbTe. It is found that, upon reducing the disorder on the lattice, the most favorable defect type changes in accordance with the observed n-to-p charge-carrier transition, representing a mechanism to tailor transport properties in PCMs by their level of disorder.