Chemical insight into electroforming of resistive switching manganite heterostructures

Abstract

We have investigated the role of the electroforming process in the establishment of resistive switching behaviour for Pt/Ti/Pr0.5Ca0.5MnO3/SrRuO3 layered heterostructures (Pt/Ti/PCMO/SRO) acting as non-volatile Resistance Random Access Memories (RRAMs). Electron spectroscopy measurements demonstrate that the higher resistance state resulting from electroforming of as-prepared devices is strictly correlated with the oxidation of the top electrode Ti layer through field-induced electromigration of oxygen ions. Conversely, PCMO exhibits oxygen depletion and downward change of the chemical potential for both resistive states. Impedance spectroscopy analysis, supported by the detailed knowledge of these effects, provides an accurate model description of the device resistive behaviour. The main contributions to the change of resistance from the as-prepared (low resistance) to the electroformed (high resistance) states are respectively due to reduced PCMO at the boundary with the Ti electrode and to the formation of an anisotropic n-p junction between the Ti and the PCMO layers.

Band alignment at memristive metal-oxide interfaces investigated by hard x-ray photoemission spectroscopy

“…1 Increasing the thickness of the Ti layer to 10 nm leaves the pristine device at low initial resistance, and the device has to be reset to a high resistance state by a negative voltage (marked in red). This "reverse-forming" can typically be observed for MIM structures fabricated from conductive metal oxides such as the Ti/Pr 1−x Ca x MnO 3 system [20] and can be a sign of a reversible electrochemical reaction between electrode and oxide [21]. For the present case, it is a strong indication that the electrical properties of the nominally insulating STFO have been altered dramatically by the deposition of the Ti electrode.…”

Resistive switching in polycrystalline YMnO3 thin films

“…28 These results supports the filamentary nature of observed unipolar resistive switching. 1,29 Increase of resistance in HRS with decrease of pad size points towards interface and/or bulk limited conductivity 30 in case of sample A. Further electrical measurements confirm that both resistance states are nonvolatile, i.e.…”

Fabrication of graphene-nanoflake/poly(4-vinylphenol) polymer nanocomposite thin film by electrohydrodynamic atomization and its application as flexible resistive switching device

“…For current-voltage (I-V) characteristics the ITO/active material/Ag device was biased by connecting Ag, the top electrode to driving voltage whereas ITO, the bottom electrode was grounded. The characterization was performed by initially applying a forming voltage, which is necessary for stable resistive switching operation [16,41,47] as shown in Fig. 7.…”