Hafnium-doped zirconia ferroelectric thin films with excellent endurance at high polarization

Using thermal atomic layer deposition and subsequent rapid thermal annealing without the need for metal clamping atop, a remanent polarization (Pr) of 25.5 μC cm-2 was achieved in a 10 nm-thick ZrO2 film deposited on a W bottom electrode. Hafnium doping was further explored to improve the ferroelectric properties in Pr as well as the endurance of zirconia-based thin films. A significantly enhanced Pr reaching 41 μC cm-2 was obtained for 10 nm-thick hafnium-doped ZrO2 with an optimal Zr : Hf ratio of 3 : 1. Importantly, owing to the greatly reduced leakage, the optimal hafnium-doped ZrO2 thin films exhibited superior retention and outstanding endurance performances at relatively high polarizations, free of serious degradation for up to 2.3 × 109-6.8 × 109 field cycles at an initial Pr of 27 μC cm-2 and were even capable of over 107 cycles at a maximum Pr of 41 μC cm-2. The superb ferroelectricities were demonstrated on big-sized capacitors as well as sub-micrometer ones, isolated or in array. This would empower zirconia-based ferroelectric thin films as a competitive front-runner for practical applications in ferroelectric-related nanoelectronics.