Deuermeier, JonasKiazadeh, AsalKlein, AndreasMartins, RodrigoFortunato, Elvira2019-06-072019-06-072019-02-192079-4991PURE: 13512022PURE UUID: 8e2d0fac-ff46-49b1-b34b-86e0c21fdfecPubMed: 30791401PubMedCentral: PMC6410279Scopus: 85071017113WOS: 000460806700158ORCID: /0000-0002-4202-7047/work/58061788ORCID: /0000-0002-8422-5762/work/115387067http://hdl.handle.net/10362/72025This research was funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT-Portuguese Foundation for Science and Technology under project number POCI-01-0145-FEDER-007688, Reference UID/CTM/50025. J.D. acknowledges funding received from the European Union's Horizon 2020 Research and Innovation Programme through the project HERACLES (Project No. 700395) and the German Science Foundation through the collaborative research center SFB 595 (Electrical Fatigue of Functional Materials). A. Kiazadeh acknowledges FCT for the postdoctoral grant SFRH/BPD/99136/2013 and for funding received through the project NeurOxide (PTDC/NAN-MAT/30812/2017).Multi-level resistive switching characteristics of a Cu₂O/Al₂O₃ bilayer device are presented. An oxidation state gradient in copper oxide induced by the fabrication process was found to play a dominant role in defining the multiple resistance states. The highly conductive grain boundaries of the copper oxide-an unusual property for an oxide semiconductor-are discussed for the first time regarding their role in the resistive switching mechanism.3342520engresistive switching memoriesmulti-level cellcopper oxidegrain boundariesaluminum oxidejournal article10.3390/nano9020289