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DF: Fachverband Dielektrische Festkörper

DF 19: Resistive switching II (jointly with DS, KR, HL)

DF 19.4: Vortrag

Freitag, 30. März 2012, 11:45–12:00, H 0111

A model for a non-volatile memory material: First principles study of Cu diffusion in α-cristobalite and α-quartz — •Martin Zelený¹, Jozsef Hegedüs¹, Adam. S. Foster², David. A. Drabold³, Stephen. R. Elliott⁴, and Risto. M. Nieminen¹ — ¹COMP/Dept. of Applied Physics, Aalto University School of Science, Espoo, Finland — ²Dept. of Physics, Tampere University of Technology, Tampere, Finland — ³Dept. of Physics and Astronomy, Ohio University, Athens, USA — ⁴Dept. of Chemistry, University of Cambridge, Cambridge, UK

The switching mechanism of a new type of non-volatile memories can be based on electrochemical metallization occurring due to the migration of Ag or Cu ions in oxide glasses as for example SiO₂. In order to clarify this mechanism, we have performed simulations of Cu diffusion in the different modifications of SiO₂. All calculations in our study were carried out based on first-principles density-functional theory using the Vienna Ab initio Simulation Package (VASP).

We present a total-energy calculation of the barrier along a diffusion path of Cu between two equivalent interstitial positions in α-cristobalite and α-quartz. Our results for α-cristobalite show that the shape of the path strongly depends on the charge of the system, but the height of the migration barrier stays between 0.15-0.2 eV. On the other hand, the height of the barrier in α-quartz varies between 0.1 and 0.6 eV and depends on the directions of Cu motion. We also present results of molecular dynamics simulations of the drift of a Cu atom driven by an external electric field.