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- ItemOperando diagnostic detection of interfacial oxygen ‘breathing’ of resistive random access memory by bulk-sensitive hard X-ray photoelectron spectroscopy(London [u.a.] : Taylor & Francis, 2019) Niu, Gang; Calka, Pauline; Huang, Peng; Sharath, Sankaramangalam Ulhas; Petzold, Stefan; Gloskovskii, Andrei; Fröhlich, Karol; Zhao, Yudi; Kan, Jinfeng; Schubert, Markus Andreas; Bärwolf, Florian; Ren, Wei; Ye, Zuo-Guang; Perez, Eduardo; Wenger, Christian; Alff, Lambert; Schroeder, ThomasThe HfO2-based resistive random access memory (RRAM) is one of the most promising candidates for non-volatile memory applications. The detection and examination of the dynamic behavior of oxygen ions/vacancies are crucial to deeply understand the microscopic physical nature of the resistive switching (RS) behavior. By using synchrotron radiation based, non-destructive and bulk-sensitive hard X-ray photoelectron spectroscopy (HAXPES), we demonstrate an operando diagnostic detection of the oxygen ‘breathing’ behavior at the oxide/metal interface, namely, oxygen migration between HfO2 and TiN during different RS periods. The results highlight the significance of oxide/metal interfaces in RRAM, even in filament-type devices. IMPACT STATEMENT: The oxygen ‘breathing’ behavior at the oxide/metal interface of filament-type resistive random access memory devices is operandoly detected using hard X-ray photoelectron spectroscopy as a diagnostic tool. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
- ItemAntiphase Boundaries Constitute Fast Cation Diffusion Paths in SrTiO3 Memristive Devices(Weinheim : Wiley-VCH, 2020) Heisig, Thomas; Kler, Joe; Du, Hongchu; Baeumer, Christoph; Hensling, Felix; Glöß, Maria; Moors, Marco; Locatelli, Andrea; Menteş, Tevfik Onur; Genuzio, Francesca; Mayer, Joachim; De Souza, Roger A.; Dittmann, ReginaResistive switching in transition metal oxide-based metal-insulator-metal structures relies on the reversible drift of ions under an applied electric field on the nanoscale. In such structures, the formation of conductive filaments is believed to be induced by the electric-field driven migration of oxygen anions, while the cation sublattice is often considered to be inactive. This simple mechanistic picture of the switching process is incomplete as both oxygen anions and metal cations have been previously identified as mobile species under device operation. Here, spectromicroscopic techniques combined with atomistic simulations to elucidate the diffusion and drift processes that take place in the resistive switching model material SrTiO3 are used. It is demonstrated that the conductive filament in epitaxial SrTiO3 devices is not homogenous but exhibits a complex microstructure. Specifically, the filament consists of a conductive Ti3+-rich region and insulating Sr-rich islands. Transmission electron microscopy shows that the Sr-rich islands emerge above Ruddlesden–Popper type antiphase boundaries. The role of these extended defects is clarified by molecular static and molecular dynamic simulations, which reveal that the Ruddlesden–Popper antiphase boundaries constitute diffusion fast-paths for Sr cations in the perovskites structure. © 2020 The Authors. Published by Wiley-VCH GmbH