Enhancing the ferroelectric performance of Hf_0.5Zr_0.5O₂ films by optimizing the incorporation of Al dopant

HfO₂-based ferroelectric (FE) thin films have gained considerable interest for memory applications due to their excellent properties. However, HfO₂-based FE films face significant reliability challenges, especially the wake-up and fatigue effects, which hinder their practical application. In this work, we fabricated 13.5 nm-thick Al-doped Hf_0.5Zr_0.5O₂ (HZO) films with both uniform (UD) and optimized (OD) Al distributions, systematically investigating the effects of Al doping distribution on their FE and endurance performances. After optimizing the Al distribution, the OD samples exhibit significantly enhanced ferroelectricity, with a robust remnant polarization (2P_r) of 53.7 μC cm⁻². Besides, compared to the undoped and UD HZO films, the OD samples exhibit enhanced dielectric performance, with lower leakage currents and higher breakdown voltages, suggesting that the optimized distribution suppresses oxygen vacancy generation and mitigates defect formation. Furthermore, the OD samples maintain a large 2P_r of 40.4 μC cm⁻² after 10^8, which can be rejuvenated back to 50.7 μC cm⁻² by higher voltage cycling. The enhanced dielectric performances and reversible phase transitions during cycling underline the potential of Al-doped HZO films with optimized distribution as reliable, long-endurance FE materials, advancing the development of HfO₂-based FE devices for future memory applications.