Regensburg 2022 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 18: Oxide Semiconductors (joint session HL/KFM)
HL 18.4: Talk
Wednesday, September 7, 2022, 10:15–10:30, H33
Simulation of Switching Processes Inside Bilayer Valence Change Memory Cells by a Drift-Diffusion Model — •Nils Sommer1, Stephan Menzel1, and Rainer Waser1,2 — 1Peter Grünberg Institut 7, Forschungszentrum Jülich, Germany — 2Institut für Werkstoffe der Elektrotechnik 2, RWTH Aachen, Germany
Valence change memory (VCM) cells are promising candidates for future nonvolatile storage devices [1]. VCM cells are characterized by their ability to switch between at least two stable resistance states by applying suitable bias voltages. A special structure of VCM cells are bilayer cells consisting of two semiconducting oxide layers, with one oxide serving as a tunnel barrier. Experiments show that a change in resistance of the cell can be caused by the exchange of oxygen between the two oxide layers [2]. However, the processes taking place are not yet well understood. We use a drift-diffusion model to simulate the movement of oxygen inside the semiconductor to gain a better understanding of the exchange process between the layers. We investigate the internal electric fields acting as a driving force on the oxygen, as well as the oxygen diffusion process that causes it to return to an equilibrium state. We show that an oxygen exchange deforms the shape of the tunnel barrier and by this changing the resistance of the cell. Further, we show that the change in resistance depends on the permittivity of the oxides.
[1] R. Waser, R. Dittmann, G. Staikov, K. Szot, Adv. Mater. 2009, 21, 2632 [2] A. Gutsche, S. Siegel, J. Zhang, S. Hambsch, R. Dittmann, Frontires in Neuroscience,2021, 15, 661261