The Interplay Between Imprint, Wake-Up Like Effects and Domains in Ferroelectric AlScN

TL;DR

This study explores the mechanisms of wake-up and imprint effects in ferroelectric AlScN films, revealing their origins, reversibility, and the influence of initial domain states on switching behavior.

Contribution

It introduces a new explanation for how initial switching cycles affect domain stabilization and imprint, and demonstrates methods to program and reverse imprint effects in AlScN.

Findings

AlScN can be considered wake-up free with inherent imprint effects.

Initial domain states influence coercive fields and switching behavior.

Domain wall motion can switch polarization after domain nucleation.

Abstract

This paper investigates wake-up and imprint in ferroelectric AlScN films. The study employs a series of I-V and P-E measurements with varying electric field amplitudes and voltage cycles as well as structural investigation via Scanning Electron Microscopy to understand the origin and underlying principle of wake-up and imprint as well as their relation. It is shown that the material can be considered wake-up free, however inherent imprint and imprint shift in combination with minor loops result in a wake-up like effect. We introduce a proposition to explain the influence of initial switching cycles on domains, their stabilization and corresponding changes in imprint. Unipolar fields and temperature investigations are used to explore the reversibility of imprint and ways to program it, while partial switching is applied to investigate domain propagation and support the aforementioned approach. It is concluded, that after an energetically more demanding domain nucleation, domain wall motion can switch the majority of polarization in Al1-xScxN. As a consequence, the presence of initial domains reduces the coercive field in respect to unipolar films.