Uncovering Two Competing Switching Mechanisms for Epitaxial and Ultrathin Strontium Titanate-Based Resistive Switching Bits

By Markus Kubicek and Rafael Schmitt and Felix Messerschmitt and Jennifer L. M. Rupp
Published in ACS Nano NULL 2015

Abstract

Resistive switches based on anionic electronic conducting oxides are promising devices to replace transistor-based memories due to their excellent scalability and low power consumption. In this study, we create a model switching system by manufacturing resistive switches based on ultrathin 5 nm, epitaxial, and grain boundary-free strontium titanate thin films with subnanometer surface roughness. For our model devices, we unveil two competing nonvolatile resistive switching processes being of different polarities: one switching in clockwise and the other in counterclockwise direction. They can be activated selectively with respect to the effective switching voltage and time applied to the device. Combined analysis of both processes with electrical DC-methods and electrochemical impedance spectroscopy reveals that the first resistive switching process is filament-based and exhibits counterclockwise bipolar resistive switching. The ROFF/RON resistance ratio of this process is extremely stable and can be tuned in the range 5

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