Defect Engineering to Achieve Wake-up Free HfO2-Based Ferroelectrics

Wake-up effect is still an obstacle in the commercialization of hafnia-based ferroelectric thin films. Herein, the effect of defects, controlled by ozone dosage, on the field cycling behavior of the atomic layer deposited Hf0.5Zr0.5O2(HZO) films is investigated. A nearly wake-up free device is achieved after reduction of carbon contamination and oxygen defects by increasing the ozone dosage. The sample which is grown at 30 s ozone pulse duration shows about 97% of the woken-upP(r)at the pristine state whereas that grown below 5 s ozone pulse time shows a pinched hysteresis loop, that underwent a large wake-up effect. This behavior is attributed to the increase in oxygen vacancy and carbon concentration in the films deposited at insufficient O(3)dosage, which is confirmed by X-ray photoelectron spectroscopy (XPS). The X-ray diffraction (XRD) scan shows that the increase in ozone pulse time yields the reduction of tetragonal phase; therefore, the dielectric constant reduces. TheI-Vmeasurements reveal the increase in current density as the ozone dosage decreases, which might be due to the generation of oxygen vacancies in the deposited film. Finally, the dynamics of wake-up effect is investigated, and it appears to be explained well by the Johnson-Mehl-Avrami-Kolmogoroff model, which is based on structural phase transformation.

Automated summary

Increasing ozone dosage can reduce carbon contamination and oxygen defects, improving the stability of the thin films and decreasing the wake-up effect. Insufficient ozone dosage leads to an increase in oxygen vacancies and carbon concentration, affecting the film performance.