Stochastic Dynamics of Resistive Switching: Fluctuations Lead to Optimal Particle Number

TL;DR

This paper models the stochastic dynamics of oxygen vacancies in resistive switching devices, revealing how fluctuations influence memory reliability and identifying an optimal vacancy number for improved performance.

Contribution

It introduces a particle-based stochastic model for resistive switching, deriving a generalized Burgers equation to interpret vacancy dynamics and analyzing fluctuation effects on memory operation.

Findings

Fluctuations significantly impact resistance state stability.

An optimal intermediate vacancy number enhances memory performance.

Nonlinear wave behavior explains collective vacancy motion.

Abstract

Resistive switching is one of the foremost candidates for building novel types of non-volatile random access memories. Any practical implementation of such a memory cell calls for a strong miniaturization, at which point fluctuations start playing a role that cannot be neglected. A detailed understanding of switching mechanisms and reliability is essential. For this reason, we formulate a particle model based on the stochastic motion of oxygen vacancies. It allows us to investigate fluctuations in the resistance states of a switch with two active zones. The vacancies' dynamics is governed by a master equation. Upon the application of a voltage pulse, the vacancies travel collectively through the switch. By deriving a generalized Burgers equation we can interpret this collective motion as nonlinear traveling waves, and numerically verify this result. Further, we define binary logical states by means of the underlying vacancy distributions, and establish a framework of writing and reading such memory element with voltage pulses. Considerations about the dis- criminability of these operations under fluctuations together with the markedness of the resistive switching effect itself lead to the conclusion, that an intermediate vacancy number is optimal for performance.