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ACS Appl Mater Interfaces. 2017 Nov 8;9(44):38643-38650. doi: 10.1021/acsami.7b10188. Epub 2017 Oct 26.

Reliable Multistate Data Storage with Low Power Consumption by Selective Oxidation of Pyramid-Structured Resistive Memory.

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KU-KIST Graduate School of Converging Science and Technology, Korea University , Seoul 02841, Korea.
Photo-Electronic Hybrids Research Center, Korea Institute of Science and Technology , Seoul 02792, Korea.
School of Chemical and Biological Engineering, Seoul National University , Seoul 08826, Korea.
Fuel Cell Research Center, Korea Institute of Science and Technology , Seoul 02792, Korea.
Department of Chemical Engineering, Soongsil University , Seoul 06978, Korea.
Department of Materials Science and Engineering, Hallym University , Chuncheon 24252, Korea.


Multilevel data storage using resistive random access memory (RRAM) has attracted significant attention for addressing the challenges associated with the rapid advances in information technologies. However, it is still difficult to secure reliable multilevel resistive switching of RRAM due to the stochastic and multiple formation of conductive filaments (CFs). Herein, we demonstrate that a single CF, derived from selective oxidation by a structured Cu active electrode, can solve the reliability issue. High-quality pyramidal Cu electrodes with a sharp tip are prepared via the template-stripping method. Morphology-dependent surface energy facilitates the oxidation of Cu atoms at the tip rather than in other regions, and the tip-enhanced electric fields can accelerate the transport of the generated Cu ions. As a result, CF growth occurs mainly at the tip of the pyramidal electrode, which is confirmed by high-resolution electron microscopy and elemental analysis. The RRAM exhibits highly uniform and low forming voltages (the average forming voltage and its standard deviation for 20 pyramid-based RRAMs are 0.645 and 0.072 V, respectively). Moreover, all multilevel resistance states for the RRAMs are clearly distinguished and show narrow distributions within 1 order of magnitude, leading to reliable cell-to-cell performance for MLC operation.


conductive filament; multilevel resistive memory; pyramidal electrode; resistive switching; surface energy; tip-enhanced electric field


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