Separation of bulk and interface contributions to electroforming and resistive switching behavior of epitaxial Fe-doped SrTiO3

We succeeded in the separation of bulk and interface contributions to the electroforming and resistive switching behavior of Pt/STO(Fe)/Nb:STO devices by performing impedance spectroscopy. Two distinctive features observed in the impedance spectra could be assigned to the STO(Fe) bulk and to the depletion layer of the Pt/STO(Fe) Schottky contact. We attribute the resistance change during the dc forming process to a local bypassing of the depletion layer caused by oxygen effusion to the environment. By comparing the impedance spectra in the resistive on and off states, we propose that the resistance of the STO(Fe)/Nb:STO interface locally changes during the switching process.