Electrode material effect on the switching behavior of ferroelectric HfO₂-based thin films

Application of HfO₂-based films to ferroelectric memory and logic devices has generated considerable interest as they allow overcoming significant problems associated with poor compatibility of perovskite ferroelectrics with CMOS processing. However, detailed studies of such application-relevant properties as imprint and polarization switching dynamics with respect to the electrode material and processing condition are still sparse in literature. Here, we use a combination of Piezoresponse Force Microscopy (PFM) and pulse switching techniques to analyze the time- and field-dependent evolution of the domain structure in Hf_0.5Zr_0.5O₂ and La:HfO₂ thin film capacitors with oxygen rich/deficient electrodes. Switching spectroscopy-PFM (SS-PFM) maps revealed the electrode-dependent spatial variations in the local potential landscape, which strongly affect the domain switching kinetics. It is shown that stronger oxidation reduces the internal imprint bias while also leading to an increase in the remanent polarization.