  Ferroelectric HfO$_2$ is a promising material for new memory devices, but
significant improvement of important properties is necessary to reach
applications. However, precedent literature shows that a dilemma between
polarization, endurance and retention exists. 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 Hf0.5Zr0.5O2
capacitors, integrated epitaxially with Si(001), present combined high
polarization (2Pr of 27 uC/cm2 in the pristine state), endurance (2Pr > 6
uC/cm2 after E11 cycles) and retention (2Pr > 12 uC/cm2 extrapolated at 10
years) using 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.
