Department of Materials Science & Metallurgy: Research paper of the month

Department of Materials Science & Metallurgy

Research paper of the month

December 2014 - Novel Electroforming-Free Nanoscaffold Memristor with Very High Uniformity, Tunability, and Density

In very simple, self-assembled nanoscaffold films containing nanocolumns with ~10-nm-radius and ~10-nm-intercolumnar-spacing, we demonstrate a new phenomenon of extraordinary, nonlinear electroresistance which leads to electroforming-free memristor behaviour at room temperature. The resistance variations exceeded two orders of magnitude, with extreme uniformity and tunability. Using electron energy loss spectroscopy, we find oxygen deficiency at the vertical heterointerfaces of nanocolumns and matrix, arising from structural incompatibility. Using conductive atomic force microscopy, we find that high conductivity is confined at vertical heterointerfaces, potentially leading to terabit integration density. Using numerical simulations, we explain the electroresistance in nanoscaffold films by the Joule-heating-accelerated drift of oxygen vacancies localized at vertical heterointerfaces. These hybrid architectures, using local ionic conduction along vertical heterointerfaces, will open up new physical functionalities in a broad range of nanoionic devices for electronics and energy applications.

Figure: Left - schematics of a nanoscaffold film causing oxygen vacancies at the vertical heterointerfaces of dissimilar crystal structures. Right - electroresistance of SrTiO3-Sm2O3 nano scaffold device.

S. Lee, A. Sangle, P. Lu, A. Chen, W. Zhang, J.S. Lee , H. Wang, Q. Jia and J.L. MacManus-Driscoll, "Novel Electroforming-Free Nanoscaffold Memristor with Very High Uniformity, Tunability, and Density" Advanced Materials (2014)

doi: 10.1002/adma.201401917