High polarization, endurance and retention in sub-5 nm Hf0.5Zr0.5O2 films

Abstract

Ferroelectric HfO₂ is a promising material for new memory devices, but significant improvement of its important properties is necessary for practical application. However, previous literature shows that a dilemma exists between polarization, endurance and retention. Since all these properties should be simultaneously high, overcoming this issue is of the highest relevance. Here, we demonstrate that high crystalline quality sub-5 nm Hf_0.5Zr_0.5O₂ capacitors, integrated epitaxially with Si(001), present combined high polarization (2P_r of 27 μC cm⁻² in the pristine state), endurance (2P_r > 6 μC cm⁻² after 10¹¹ cycles) and retention (2P_r > 12 μC cm⁻² extrapolated at 10 years) using the same poling conditions (2.5 V). This achievement is demonstrated in films thinner than 5 nm, thus opening bright possibilities in ferroelectric tunnel junctions and other devices.