Area-dependent electroforming and switching polarity reversal across TiO2/Nb:SrTiO3 oxide interfaces
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Vacancy-mediated transport drives the functionality of oxide-based nonvolatile memristive devices. Here, we report the size dependence of TiO2/Nb:STO heterojunctions for electroforming and the subsequent resistive switching process. Conductive AFM measurements suggest that the forming and reset voltages both decrease with increasing junction size. We also show oxygen flow ratio changes during fabrication, and post-annealing impacts the set voltage and resistance ratio through changes in available oxygen vacancies. Finally, a polarity reversal between eight-wise and counter-eight-wise switching occurs after vacuum and ambient anneals, thus modulating oxygen vacancy availability and changing (reversibly) the mechanism from vacancy migration to an electron trap/detrap process.
KeywordsOxygen Vacancy Resistive Switching TiO2 Thin Film Resistance Ratio High Resistance State
This research was partially supported by University of Massachusetts-Amherst start-up funding and the UMass Center for Hierarchical Manufacturing (CHM), a NSF Nanoscale Science and Engineering Center (CMMI-1025020). The authors also acknowledge use of the facilities at the CHM Conte Nanotechnology Cleanroom for thin-film deposition and lithography processes.
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