Probing the oxygen vacancy distribution in resistive switching Fe-SrTiO3 metal-insulator-metal-structures by micro-x ray absorption near-edge structure

Resistive switching metal-insulator-metal structures were fabricated from epitaxial Fe-doped SrTiO3 thin films to study the distribution of oxygen vacancies in a switched memristor cell using a micro-focused x-ray beam. In addition to the main filament, we found that the concentration of oxygen vacancies increases homogeneously over the whole electrode area during the electroforming procedure. The x-ray absorption near-edge structure (XANES) observed at the location of the filament exhibits distinct differences to the surrounding area, which are interpreted with full-multiple-scattering XANES calculations to derive from oxygen vacancy clustering in the first coordination shell around Fe. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3699315]