Interfacial ‘dead’ layers between metals and ferroelectric thin films generally induce detrimental effects in nanocapacitors, yet their peculiar properties can prove advantageous in other electronic devices. Here, we show that dead layers with low Li concentration located at the surface of LiNbO3 ferroelectric materials can function as unipolar selectors. LiNbO3 mesa cells were etched from a single-crystal LiNbO3 substrate, and Pt metal contacts were deposited on their sides. Poling induced non-volatile switching of ferroelectric domains in the cell, and volatile switching in the domains in the interfacial (dead) layers, with the domain walls created within the substrate being electrically conductive. These features were also confirmed using single-crystal LiNbO3 thin films bonded to SiO2/Si wafers. The fabricated nanoscale mesa-structured memory cell with an embedded interfacial-layer selector shows a high on-to-off ratio (>106) and high switching endurance (~1010 cycles), showing potential for the fabrication of crossbar arrays of ferroelectric domain wall memories.
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The data sets generated and analysed during this study are available from the corresponding authors on reasonable request. Source data for Figs. 1–5 and for the figures and tables in the Supplementary Information are provided with the paper.
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This work was supported by the Basic Research Project of Shanghai Science and Technology Innovation Action (grant number 17JC1400300), the National Key R&D Programme of China (number 2019YFA0308500), the National Natural Science Foundation of China (grant numbers 61674044 and 11572040), the Programme of Shanghai Subject Chief Scientist (grant number 17XD1400800) and the Beijing Natural Science Foundation (grant number Z190011). J.F.S. acknowledges the financial support of the Strategic Priority Research Programme of the Chinese Academy of Sciences (grant number XDB07030200). C.S.H. acknowledges the support by Samsung Research Funding & Incubation Center of Samsung Electronics under project number SRFC-TA1703-02. Theoretical calculations were performed using resources of the National Supercomputer Centre in Guangzhou. We thank D. MacDonald from Liwen Bianji, Edanz Editing China (www.liwenbianji.cn/ac), for editing the English text of a draft of this manuscript. This work is dedicated to the memory of J.F.S., who passed away on 6 April 2020.
The authors declare no competing interests.
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Jiang, A.Q., Geng, W.P., Lv, P. et al. Ferroelectric domain wall memory with embedded selector realized in LiNbO3 single crystals integrated on Si wafers. Nat. Mater. (2020). https://doi.org/10.1038/s41563-020-0702-z