Simple, Inexpensive, and Rapid Approach to Fabricate Cross-Shaped Memristors Using an Inorganic-Nanowire-Digital-Alignment Technique and a One-Step Reduction Process

Significance Statement

Non-volatile resistive memory (memristor) has received considerable attention because of its non-volatility, faster access speed, ultra-high density and easy fabrication process. It is regarded as one of the most attractive candidates to meet the trend of aggressively reduced feature size of electronic devices as predicted by Moore’s law in the next a few decades. One-dimensional (1D) nanowires (NWs) are one possibility that would allow researchers to fully exploit the scaling potential of high density memory arrays. Several research groups have investigated the feasibility of applying NWs to memristors. However, scalable fabrication of NW array with alignment is still a difficult challenge.

This work provides a new fabrication approach, named as inorganic-nanowire digital-alignment technique (INDAT). INDAT is a rapid and simple printing technology that succeeds in printing Cu NWs with various shapes, such as parallel lines with adjustable pitch, grids and waves. Through one-step selective reduction process, the grids are converted memristor array with cross-bar-shaped conductive Cu nanowires jointed with a nanometer-scale CuxO layer. The devices exhibited excellent electrical performance with reproducible resistive switching behavior. This work can offer a future stretchable memory for integration into textile to serve as a basic building block for smart fabrics and wearable electronics.

Simple, Inexpensive, and Rapid Approach to Fabricate Cross-Shaped Memristors Using an Inorganic-Nanowire-Digital-Alignment Technique and a One-Step Reduction Process. Advances in Engineering

About the author

Wentao Xu is a research associate professor in the department of Materials Science and Engineering at Pohang University of Science and Technology (POSTECH), Korea. He received his PhD in Chemical Engineering from POSTECH in February 2012. His research interests include graphene electronics, synapse emulating electronic devices, nonvolatile memory devices and organic field-effect transistors. 

About the author

Yeongjun Lee received his B.S. in material science & engineering from Hanyang University in 2012 and M.S. in material science & engineering from Pohang University of Science and Technology (POSTECH) in 2014, and now he is a Ph.D. candidate in the same institute. He has been researched on nanowire electronics, printed electronics and bio-healthcare devices. 

About the author

Sung-Yong Min received his B.S. in Materials Science and Engineering in 2010 from Pohang University of Science and Technology (POSTECH), and PhD in Materials Science and Engineering in 2015 from POSTECH. He then joined Polymer Research Institute in POSTECH as a postdoctoral researcher in 2015. His current research work is focused on controllable metallic wire printing for all-wire electronics. 

About the author

Cheolmin Park is a Full Professor of the Department of Materials Science and Engineering at Yonsei University. He received his BS in Textile Engineering in 1992 and the MS in Polymer and Fiber Science in 1995 from the Seoul National University, and PhD in Materials Science and Engineering from Massachusetts Institute of Technology (with E.L. Thomas) in 2001. From 2001 to 2002, he was a post-doctoral fellow in chemistry and chemical biology of Harvard University. He joined the Department of Metallurgical System Engineering of Yonsei University in 2002. His research interests include polymer physics, self assembled block copolymers, ferroelectric materials, micro- and nanofabrication, and polymeric opto-electronic devices such as memories and transistors. (Source http://www.inderscienceonline.com/doi/abs/10.1504/IJNT.2013.054212). 

About the author

Tae-Woo Lee is an associate professor in the department of Materials Science and Engineering at POSTECH, Korea. He received his PhD in Chemical Engineering from Korea Advanced Institute of Science and Technology (KAIST), Korea, in February 2002. He then joined Bell Laboratories, USA, as a postdoctoral researcher in 2002. From September 2003 to August 2008, he worked in the Samsung Advanced Institute of Technology as a member of research staff. He received a prestigious Korea Young Scientist Award from the President of Korea in 2008 and The Scientist of the Month Award from the Ministry of Science, ICT and Future Planning in 2013. His research focuses on printed and organic electronics based on organic and carbon materials for flexible electronics, displays, solid-state lightings, and solar energy conversion devices. 

Journal Reference

Advanced Materials, January 2016, Volume 28, Issue 3, pp 527-532.

Wentao Xu,1 Yeongjun Lee,1 Sung-Yong Min,1 Cheolmin Park,2 Tae-Woo Lee1

Show Affiliations

1Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk 790-784, Republic of Korea

2Department of Materials Science and Engineering, Yonsei University, Seoul 120-749, Republic of Korea 

 

Abstract

We report a simple, inexpensive, and rapid method to fabricate two-dimensional arrays of perpendicularly-aligned, individually-conductive Cu nanowires that sandwich a nanometer-scale CuxO layer at each cross point. Large-scale long continuous Cu-precursor-blended NWs that were digitally printed with computer-digital alignment on a large area, followed by oxidation and a selective reduction process, which converts NWs to copper but preserves the oxide layer in the joint areas, thereby producing Cu-NW arrays composed of perpendicular conductive Cu-NWs sandwiching a nanometer-scale CuxO layer at each cross point. In this approach, the oxide layer was self-formed and patterned, so this approach avoids the troublesome conventional deposition and lithographic processes. The approach uses inorganic-nanowire-digital-alignment technique (INDAT) which solves the alignment and scalable fabrication difficulties of currently-available inorganic nanowire techniques. This economic approach maintains all expensive metals in the final product, unlike conventional approaches in which most of the deposited metal is peeled off. The resulting arrays had reproducible resistive switching behavior, high on/off current ratio~106 and extensive cycling endurance. This is the first report of memristors in which the resistive switching oxide layer was self-formed, self-patterned and self-positioned, and we envision that the new features of the technique will provide great opportunities for future nano-electronic circuits.

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