Polarization switching kinetics of the ferroelectric Al-doped HfO2 thin films prepared by atomic layer deposition with different ozone doses

Abstract

Ferroelectric switching kinetics of the Al-doped HfO2 (Al:HfO2) thin films prepared by the atomic layer deposition process were investigated by varying the dose time of oxygen precursor (O3). When the O3 dose time was reduced to 3 s, the Al:HfO2 films exhibited an enhanced remnant polarization (2Pr) of 10.2 μC/cm2 due to the suppression of the monoclinic phase and the increase in the ratio of oxygen vacancy. Double-pulse switching and the Kolmogorov–Avrami–Ishibashi model were used to obtain detailed quantitative information on the switching kinetics of the Al:HfO2 films. The estimated values of switching time and activation energy showed the strong dependence of O3 dose. This suggests that the O3 dose condition can be a key control parameter to modulate the ferroelectric polarization switching dynamics of the Al:HfO2 thin films.

Impact of vacancies and impurities on ferroelectricity in PVD- and ALD-grown HfO2 films

“…For ALD 10 s , we still find a tiny Hf 3þ component that disappears completely after a longer ozone dose in ALD 60 s , in agreement with recent findings. 14 Figure 4 shows the Hf 4s and O 1s core levels, which have been normalized to the Hf 4s peak. The O 1s peak intensity shows a gradual increase from PVD 0 sccm , PVD 2 sccm , ALD 60 s to ALD 10 s .…”

Interplay between oxygen defects and dopants: effect on structure and performance of HfO2-based ferroelectrics

“…The trends for the formation of the monoclinic phase were encountered also for other doped HfO 2 systems. Yoon et al 18 deposited aluminium doped HfO 2 via ALD with 3, 5 and 10 s O 3 dose time. As displayed in Fig.…”

“…They explained this observation by correlating the oxygen partial pressure to the energy barrier between the tetragonal and the orthorhombic phase, which is lower for lower oxygen content as a result of po-phase stabilization through oxygen vacancies. Yoon et al 18 studied the effect of the ozone dose time on the activation energy for the switching of aluminium doped HfO 2 films. Despite using a different model for the description of the collected experimental evidence (Kolmogorov-Avrami-Ishibashi) and a different deposition technique, they similarly observed how this value increased for longer oxygen exposure.…”

“…97 V O were shown to have a strong influence on field cycling behaviour as observed Table 3 Summary of the activation energy for polarization switching as experimentally calculated. 18,49 Oxygen poor and oxygen rich stand for the minimum and the maximum oxygen supply during deposition, respectively…”

“…Despite oxygen being heavily discussed as a key parameter for phase stabilization and reliability control both in traditional perovskite ferroelectrics and in newer HfO 2 -based materials, only lately the effect of the oxygen supply during film deposition has started to be studied systematically by tuning film growth processing parameters. [16][17][18] Within this review, first a general overview of oxygen related defects in oxides is presented. The next section presents the impact of the amount of these defects in terms of oxygen supply during deposition as shown through existing literature reports for undoped HfO 2 and differently doped HfO 2 layers.…”