Three-Dimensional Observation of the Conductive Filamentin Nanoscaled Resistive Memory Devices.

The basic unit of information infilamentary-based resistive switchingmemories is physically stored in a conductive filament. Therefore,the overall performance of the device is indissolubly related to theproperties of such filament. In this Letter, we report for the firsttime on the three-dimensional (3D) observation of the shape of theconductive filament. The observation of the filament is done in ananoscale conductive-bridging device, which is programmed under realoperative conditions. To obtain the 3D-information we developed adedicated tomography technique based on conductive atomic force microscopy.The shape and size of the conductive filament are obtained in three-dimensionswith nanometric resolution. The observed filament presents a conicalshape with the narrow part close to the inert-electrode. On the basisof this shape, we conclude that the dynamic filament-growth is limitedby the cation transport. In addition, we demonstrate the role of theprogramming current, which clearly influences the physical-volumeof the induced conductive filaments. [ABSTRACT FROM AUTHOR]