Memristor based on phase-changed Cu nanowires and the operando characterization using focused synchrotron radiation beam

Ling Lee^1*, Yu-Chuan Shih¹, Ying-Chun Shen¹, Yu-Lun Chueh¹

¹Department of Materials Science and Enineering, National Tsing Hua University, Taiwan

* Presenter:Ling Lee, email:leeling0430@gmail.com

Currently, we have demonstrated a current-induced phase change method of Cu nanowires in the ambient environment, and succeed in a reversible resistive switching up to 100 cycles with a large ON/OFF ratio (> 10³) between high- and low-resistance states and a low threshold voltage (< 1 V). For the purpose to understand the origin of the memristor behavior, operando x-ray absorption near edge spectroscopy (XANES) based on a focused synchrotron radiation beam with spot size of several tens of nanometer was performed in this work.
As for the fresh nanowire, a clear feature of Cu is observed where the position of absorption edge is at 8,979 eV. After the oxidation, the absorption edge increased to 8,980 eV, which is identical to the absorption edge of Cu₂O. On the contrary, both the feature of Cu and Cu₂O were observed at the above-edge XANES spectrum. Finally, once the resistance of nanowire is switched from the high resistance state to the low resistance one, the absorption edge energy decreases as well. Furthermore, owing to the capability of the spatial resolved mapping using focused synchrotron radiation beam, x-ray photoelectron spectroscopy and diffraction were also performed. In brief, the operando investigations realize the distribution of the oxidation site and provide effective information of the origin of the reversible resistive switching owing to the partial phase change.

Keywords: resistive switching, Cu nanowire, current-induced oxidization, focused synchrotron radiation beam, XANES