Reproducible Resistance Switching in Ni/NiO/Ni Trilayer
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0997-I07-08
Reproducible Resistance Switching in Ni/NiO/Ni Trilayer Hisashi Shima1, Fumiyoshi Takano1, Hiro Akinaga1, Isao H Inoue2, and Hidenori Takagi2,3 1 Nanotechnology Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 2, 1-1-1 Umezono, Tsukuba, 305-8568, Japan 2 Correlated Electron Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8562, Japan 3 Department of Advanced Materials, University of Tokyo, Kashiwa, 277-8581, Japan ABSTRACT The reproducible resistance switching behavior in Pt/NiO/Pt and Ni/NiO/Ni trilayers have been investigated. The characteristic resistance switching processes, reset and set processes after forming, have analogously observed in the Ni/Ni-O/Ni trilayer compared to those in the Pt/Ni-O/Pt trilayers. Furthermore, in both the trilayers, resistance in the low resistance state is independent of the electrode area, while that in the high resistance state increases with decreasing the electrode area. Consequently, the resistance switching ratio in the smaller electrode area is larger, which is preferable in increasing information density of RRAM. In conclusion, Ni/Ni-O/Ni is a quite promising trilayer structure for RRAM because the large reproducible resistance switching ratio is obtainable without using precious metal electrodes. INTRODUCTION Recently, oxide materials showing large reproducible resistance switching in the metal/oxide/metal trilayer structure have drawn much attention in development of resistance random access memory (RRAMTM) [1-6]. Especially, the binary transition metal oxide such as Ni-O, Cu-O, Co-O, and Ti-O is intensively investigated toward the practical application [1-4]. It should be noted that the compatibility with conventional complimentary metal oxide semiconductor technologies is required from the practical point of view. For that reason, we have focused on the binary transition metal oxides. Furthermore, the materials used as an electrode should have the practicality without degrading the resistance switching properties. Therefore, the affordable metal electrodes compared to the precious metal Pt have used in the present report. The resistance switching behaviors in the trilayer consisting of Ni and Ni oxide are demonstrated. EXPERIMENT Pt/NiO/Pt and Ni/NiO/Ni trilayers were grown on the thermally oxidized Si substrate at room temperature by magnetron sputtering. In depositing NiO layers, NiO target was used and purified Ar gas was introduced in the chamber. The total pressure and rf power for the NiO deposition were 0.5 Pa and 200 W, respectively. The thickness of Ni, Pt, and NiO layer is 100, 100, and 50 nm, respectively. Before depositing the bottom electrode, Ti was sputtered as adhesion. The crystallographic orientation was investigated by X-ray diffraction. The valance state of Ni ion in NiO was investigated by the X-ray photoelectron spectroscopy, with the incident angle of 90 degree. The rectangular resist patterns were drawn on the top electrode
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