Controlling the Wake-Up Mechanism and Switching Kinetics of Ferroelectric Hf x Zr1 – x O2 through Hf Content Modulation

TL;DR

This paper explores how adjusting the hafnium content in Hf x Zr1 - x O2 thin films affects their switching behavior and wake-up mechanisms, which is important for memory and computing devices.

Contribution

The study reveals that increasing Hf content shifts the wake-up mechanism from phase transition to ferroelastic domain switching.

Findings

Multiple wake-up mechanisms coexist in Hf x Zr1 - x O2 thin films.

Higher Hf content leads to faster polarization switching and controllable partial polarization states.

Disorder-driven domain nucleation and nonlinear domain wall dynamics are influenced by Hf composition.

Abstract

The excellent scalability
and compatibility to current
CMOS manufacturing
processes make ferroelectric Hf
x
Zr1 –

x
O2 thin
films a promising candidate for embedded nonvolatile memories, as
well as for synaptic devices in neuro-inspired computing. In order
to achieve precise control over the polarization states and to ensure
reliable operation in these thin films, a thorough understanding of
the film’s domain switching kinetics and behavior under field
cycling is necessary. The Hf composition in Hf
x
Zr1 – x
O2 thin films plays a crucial role in determining the disorders, phase
composition, and crystallographic texture within the film when integrated
in a metal–ferroelectric–metal (MFM) device, all of
which affect the evolution of its field cycling response and switching
kinetics. In this work, the impact of Hf content on wake-up and domain
switching kinetics in Hf
x
Zr1 – x
O2 thin films is investigated, and the
physical mechanisms behind these differences are explored. This study
highlights that multiple wake-up mechanisms can coexist in the same
film and that as the Hf composition is increased, the dominant physical
mechanism of wake-up in the film changes from a field-induced phase
transition to field-induced ferroelastic domain switching. Furthermore,
since the inhomogeneity within the ferroelectric film depends on Hf
composition, the speed of polarization switching and the available
partial polarization states in the film can be precisely controlled
as a function of Hf content due to the disorder-driven domain nucleation
and nonlinear domain wall dynamics.

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