Improvement of endurance and switching speed in Hf_1-ZrO₂thin films using a nanolaminate structure

To improve the endurance and polarization switching speed of Hf_1-ZrO₂(HZO) ferroelectric films, we designed a 10 nm Hf_0.5Zr_0.5O₂ + ZrO₂(HZZ) nanolaminate structure. Three films with different ZrO₂interlayers thicknesses were compared to find the optimal condition to implement the effect of the topological domain wall which was proposed recently. The HZZ film were deposited by repeatedly stacking ten HZO (∼0.92 nm) and six ZrO₂(∼0.53 nm) layers; they exhibited a dramatic reduction of coercive field without an effective loss of remnant polarization. The endurance at operation voltage increased by more than 100 times compared with that of the solid solution HZO film, and the switching speed was increased by more than two times. The formation of the tetragonal phase-like spacer between the ferroelectric polar regions appears to be the main factor associated with the reduction of the switching barrier and leads to the acceleration of the switching propagation over multiple domains.