  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.
