Defect engineering for control of wake-up effect in HfO2-based ferroelectrics

TL;DR

This study demonstrates that controlling defects via ozone dosage during deposition can significantly reduce the wake-up effect in HfO2-based ferroelectric films, improving their stability for device applications.

Contribution

It introduces defect engineering through ozone dosage control as a method to mitigate wake-up effects in hafnia-based ferroelectrics.

Findings

Higher ozone dosage reduces oxygen vacancies and carbon contamination.

Nearly wake-up free ferroelectric devices achieved with optimized ozone treatment.

The wake-up behavior is well explained by the Johnson-Mehl-Avrami-Kolmogoroff model.

Abstract

Wake-up effect is still an obstacle in the commercialization of hafnia-based ferroelectric thin films. In this work, we investigate the effect of defects, controlled by ozone dosage, on the field cycling behavior of the atomic layer deposited Hf0.5Zr0.5O2 (HZO) films. A nearly wake-up free device was achieved after reduction of carbon contamination and oxygen defects by increasing the ozone dosage. The sample which was grown at 30 sec ozone pulse duration shows about 98% of the woken-up Pr at the pristine state while those grown below 5 sec ozone pulse time show a pinched hysteresis loop, undergone a large wake-up effect. This behavior is attributed to the increase in oxygen vacancy and carbon concentration in the films deposited at insufficient O3 dosage which was confirmed by x-ray photoelectron spectroscopy (XPS). X-ray diffraction (XRD) scan shows that the increase of ozone pulse time yields in the reduction of tetragonal phase; therefore, the dielectric constant reduces. The I-V measurements reveal the increase of current density as the ozone dosage decreases which might be due to the generation of oxygen vacancies in the deposited film. Finally, we have investigated the dynamics of wake-up effect and it appears to be explained well by Johnson-Mehl-Avrami-Kolmogoroff model which is based on structural phase transformation.