| AVS 64th International Symposium & Exhibition | |
| Novel Trends in Synchrotron and FEL-Based Analysis Focus Topic | Wednesday Sessions |
| Session SA+AS+HC+SS-WeA |
| Session: | In Situ and Operando Characterization of Interfacial Reactions in Energy & Electronic Devices |
| Presenter: | Christoph Baeumer, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany |
| Authors: | R. Dittmann, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany C. Baeumer, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany D. Cooper, Université Grenoble Alpes & CEA, LETI, Minatec Campus, Grenoble, France C. Schmitz, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany S. Menzel, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany C.M. Schneider, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany R. Waser, Peter Gruenberg Institute, Forschungszentrum Juelich GmbH, Juelich, Germany |
| Correspondent: | Click to Email |
Memristive devices based on resistive switching in transition metal oxides are attractive candidates for next-generation non-volatile memory applications. It is suspected that voltage-driven oxygen-ion migration and the resulting nanoscale redox processes drive the resistance change in these materials1, 2. Direct observation and quantification of the switching mechanism itself, however, remain challenging because the net changes of structure, stoichiometry, and valence state during switching are very small and occur primarily at electrode interfaces or within nanoscale filaments.
Here we will present local changes in the chemical and electronic structure of SrTiO3-based memristive devices utilizing in operando characterization tools like transmission electron microscopy (TEM) and photoemission electron microscopy (PEEM). SrTiO3 is chosen as a single crystalline model material, which offers a well-understood platform and well-characterized spectroscopic signatures.
To overcome the surface sensitivity typically limiting PEEM investigations of memristive devices, photoelectron-transparent graphene top electrodes are used to attain spectroscopic information from the buried SrTiO3 layer3. During in situ switching, reversible changes of the O K-edge absorption spectra within spatially confined regions provide a quantitative map of the oxygen vacancy concentration, confirming that the resistance change is caused by localized oxygen evolution and reincorporation reactions rather than purely internal movement of oxygen vacancies4.
A remarkable agreement between experimental quantification of the redox state and device simulation reveals that changes in oxygen vacancy concentration by a factor of 2 at electrode-oxide interfaces cause a modulation of the effective Schottky barrier and lead to >2 orders of magnitude change in device resistance. These findings allow realistic device simulations, opening a route to less empirical and more predictive design of future memory cells.
1 R. Waser and M. Aono, Nat. Mater. 6, 833 (2007).
2 R. Waser, R. Dittmann, G. Staikov, and K. Szot, Adv. Mater. 21, 2632 (2009).
3 C. Baeumer, C. Schmitz, A. Marchewka, D. N. Mueller, R. Valenta, J. Hackl, N. Raab, S. P. Rogers, M. I. Khan, S. Nemsak, M. Shim, S. Menzel, C. M. Schneider, R. Waser, and R. Dittmann, Nat. Commun. 7, 12398 (2016).
4 C. Baeumer, C. Schmitz, A. H. H. Ramadan, H. Du, K. Skaja, V. Feyer, P. Muller, B. Arndt, C. Jia, J. Mayer, R. A. De Souza, C. Michael Schneider, R. Waser, and R. Dittmann, Nat. Commun. 6, 9610 (2015).