A Study of Apparent Symmetry Breakdown in Perovskite Oxide-based Symmetric RRAM Devices

TL;DR

This paper introduces a new symmetric RRAM device model based on Perovskite oxide thin films, explaining apparent symmetry breakdown during resistance switching and confirming the model with experimental data.

Contribution

A novel symmetric RRAM model based on PCMO material explains resistance switching behavior and symmetry breakdown, supported by experimental validation.

Findings

Device exhibits resistance switching with voltage polarity changes

Model's hysteresis curve matches experimental data

Symmetry breakdown is due to resistance changes near electrodes

Abstract

A new model of a symmetric two-terminal non-volatile RRAM device based on Perovskite oxide thin film materials, specifically Pr1-xCaxMnO3 (PCMO), is proposed and analyzed. The model consists of two identical half-parts, which are completely characterized by the same resistance verses pulse voltage hysteresis loop, connected together in series. Even though the modeled device is physically symmetric with respect to the direction of current, it is found to exhibit switching of the resistance with the application of voltage pulses of sufficient amplitude and of different polarities. The apparent breakdown of parity conservation of the device is attributed to changes in resistance of the active material layer near the electrodes during switching. Thus the switching is history dependent, a feature that can be very useful for the construction of real non-volatile memory devices. An actual symmetric device, not previously reported in the literature and based on the proposed model, is fabricated in the PCMO material system. Measurements of the resistance of this new device generated an experimental hysteresis curve that matches well the calculated hysteresis curve of the model, thus confirming the features predicated by the new symmetric model.