Effect of Lanthanum-Aluminum Co-Doping on Structure of Hafnium Oxide Ferroelectric Crystals.

Hafnium oxide (HfO)-based devices have been extensively evaluated for high-speed and low-power memory applications. Here, the influence of aluminum (Al) and lanthanum (La) co-doping HfO thin films on the ferroelectric characteristics of hafnium-based devices is investigated. Among devices with different La/Al ratios, the Al and La co-doped hafnium oxide (HfAlAO) device with 4.2% Al and 2.17% La exhibited the excellent remanent polarization and thermostability. Meanwhile, first principal analyses verified that hafnium-based thin films with 4.2% Al and 2.17% La promoted the formation of the o-phase against the paraelectric phase, providing theoretical support for supporting experimental results. Furthermore, a vertical ferroelectric HfO memory based on 3D macaroni architecture is reported. The devices show excellent ferroelectric characteristics of 22 µC cm under 4.5 MV cm and minimal coercive field of ≈1.6 V. In addition, the devices exhibit great memory performance, including the response speed of device can achieve 20 ns and endurance characteristic can achieve 10 cycles.