Guidelines for the Optimization of Hafnia-Based Ferroelectrics through Superlattice Engineering.

Hafnia-based ferroelectrics are revolutionizing the data storage industry and the field of ferroelectrics, with improved materials and devices being reported monthly. However, full understanding and control have not been reached yet, and the ideal material still needs to be found. Here, we report ferroelectric hafnia-zirconia superlattices made out of zirconium-substituted hafnia (Hf1-x Zr x O2) sublayers of varying stoichiometries alternating with pure ZrO2 sublayers. It is observed that the ZrO2 layers in these superlattices act as a booster for total remnant polarization (P r). By combining the benefits of the ZrO2 layers and the added interfaces, which help prevent breakdown, we fabricate superlattices with a total 87.5% ZrO2 content, exhibiting record polarizations with a 2P r value of 84 μC/cm2 that can be cycled 109 times while maintaining a 2P r > 20 μC/cm2. Next to these attractive properties, substitution of HfO2 by the much more abundant ZrO2 offers a significant step toward the sustainable application of these devices.