Simulation of TiN/HfO2/Pt memristor I–V curve for different conductive filament thickness

Andrey N Aleshin,Nikolay V Zenchenko,Oleg A Ruban

doi:10.3897/j.moem.7.2.73289

Abstract

The operation of the TiN/HfO2/Pt bipolar memristor has been simulated by the finite elements method using the Maxwell steady state equations as a mathematical basis. The simulation provided knowledge of the effect of conductive filament thickness on the shape of the I–V curve. The conductive filament has been considered as the highly conductive Hf ion enriched HfOx phase (x &lt; 2) whose structure is similar to a Magneli phase. In this work a mechanism has been developed describing the formation, growth and dissolution of the HfOx phase in bipolar mode of memristor operation which provides for oxygen vacancy flux control. The conductive filament has a cylindrical shape with the radius varying within 5–10 nm. An increase in the thickness of the conductive filament leads to an increase in the area of the hysteresis loop of the I–V curve due to an increase in the energy output during memristor operation. A model has been developed which allows quantitative calculations and hence can be used for the design of bipolar memristors and assessment of memristor heat loss during operation.

Highlights

Researchers currently show strong interest to new computer technologies such as quantum computers and neuromorphic systems
The operation of the TiN/HfO2/Pt bipolar memristor was simulated by the finite elements method using the Maxwell steady state equations as a mathematical basis
The memristor operation mode included four sequential time intervals corresponding to different sections of the bipolar signal having a triangular shape

Summary

Introduction

Researchers currently show strong interest to new computer technologies such as quantum computers and neuromorphic systems. Memristor operation mode switching is achieved due to the formation and destruction of conductive filaments in the memristor working body. The aim of this work is to study the effect of conductive filament thickness on the shape of the I–V curve for a TiN/HfO2/Pt bipolar memristor by numerical simulation of memristor operation mode with the finite elements method using the Maxwell steady state equations as a mathematical basis. This approach can be referred to as “first principle” simulation of I–V curves. Hafnium oxide is widely used for the fabrication of bipolar memristors in which unlike titanium oxide based memristors a wider range of electrode pairs are used, i.e., Hf–TiN [3, 9], Pt–TiN [10], TiN–TiN [11, 12] and Ni–TaN [13], this simplifying the choice of electrodes for the simulation of bipolar memristor operation

Memristor model

Choice of memristor electrode material

I–V curve construction

Conclusion