Dresden 2014 – scientific programme
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DS: Fachverband Dünne Schichten
DS 44: Poster III: Focus session: Resistive switching by redox and phase change phenomena
DS 44.2: Poster
Thursday, April 3, 2014, 16:00–19:00, P1
High resolution electrocoloration study of Fe:STO single crystals — •Viktor Havel1, Astrid Marchewka1, Stephan Menzel2, Susanne Hoffmann-Eifert2, and Rainer Waser1,2 — 1Institut für Werkstoffe der Elektrotechnik II, RWTH Aachen University, Germany — 2Forschungszentrum Jülich GmbH, PGI 7, Jülich, Germany
Strontium titanate (STO) single crystals and thin films are utilized as model materials for the understanding of the resistive switching (RS) mechanism of valence change oxides like TiOx, HfOx and TaOx. Prior to the bipolar RS an electroforming step is typically required, which impacts the device performance. A thorough understanding of the physical processes involved in the electroforming step is fundamental for future device optimization.
In this study, the electroforming process in Fe doped STO single crystals is made optically visible. Color changes in the transparent Fe:STO crystals are caused by a valence change of the Fe ions as a result of a local redox processes. Thus, the Fe redox reaction is utilized as an indirect proof of the oxygen vacancy drift-diffusion in the crystal. The custom designed electrocoloration set-up enables to put the samples under temperature and electrical stress, to measure the current and resistance change over time and in parallel to monitor the evolution of the color front by high resolution optical microscopy.
The results are discussed on the basis of 1D drift-diffusion simulations of the temporal evolution of the oxygen vacancy distribution, which represent the initial progress of the virtual cathode region.
This work was supported in part by the DFG (SFB917).