Hierarchical Domain Structure and Extremely Large Wall Current in Epitaxial BiFeO ₃ Thin Films

Journal Article · Wed Jun 06 00:00:00 EDT 2018 · Advanced Functional Materials

DOI:https://doi.org/10.1002/adfm.201801725· OSTI ID:1440787

Bai, Zi Long ^[1]; Cheng, Xiao Xing ^[2]; Chen, Dong Fang ^[1]; Zhang, David Wei ^[1]; Chen, Long‐Qing ^[2]; Scott, James F. ^[3]; Hwang, Cheol Seong ^[4]; Jiang, An Quan  ^[1]

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1. State Key Laboratory of ASIC and System School of Microelectronics Fudan University Shanghai 200433 China
2. Department of Materials Science and Engineering The Pennsylvania State University University Park PA 16802 USA
3. Department of Chemistry St. Andrews University KY16 9ST St. Andrews UK, Department of Physics St. Andrews University KY16 9ST St. Andrews UK
4. Department of Materials Science and Engineering Seoul National University Seoul 151‐744 Korea, Inter‐University Semiconductor Research Center Seoul National University Seoul 151‐744 Korea

Abstract Erasable electrical conductive domain walls in an insulating ferroelectric matrix provide novel functionalities for applications in logic and memory devices. The crux of such success requires sufficiently high wall currents to drive high‐speed and high‐power nanodevices. This work provides an appealing strategy to increase the current by two orders of magnitude through the careful selection of current flowing paths along the charged walls. The dense walls come into form through the hierarchical evolution of the 71°, 109°, and 180° domains of epitaxial BiFeO ₃ films in a planar‐geometry ferroelectric resistance‐switching memory cell. The engineered films grown on SrTiO ₃ and GdScO ₃ substrates allow the observation of detailed local configurations and the evolution of the different domain types using vector piezo‐force microscopy. The higher local electrical conductivity near the charged domain walls is identified by conductive atomic‐force microscopy. It is shown that 180° domain reversal proceeds by three‐step 71° rotations of the pristine domains. Surprisingly, a maximum current of ≈300 nA is observed for current paths along charge‐uncompensated head‐to‐head hierarchical domain walls connecting the two electrodes on the film surface. Furthermore, the achievable current level can be conveniently controlled by varying the relative directions of the initial polarization and the applied field.

• Sponsoring Organization: USDOE
• Grant/Contract Number: DE‐FG02‐07ER46417
• OSTI ID: 1440787
• Journal Information: Advanced Functional Materials, Journal Name: Advanced Functional Materials Vol. 28 Journal Issue: 31; ISSN 1616-301X
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English