Achieving High-Endurance Ferroelectricity in Hf0.5Zr0.5O2 Thin Films on Ge Substrate Through ZrO2 Interfacial Layer Induced Low-Temperature Annealing

Ferroelectric Hf0.5Zr0.5O2 (HZO) thin films on Ge substrates often experience limited endurance under field cycling. Lowering the annealing temperature can be an effective approach but may potentially compromise the ferroelectric properties. In this study, ZrO2 is selected as an interfacial layer between HZO and Ge substrate, successfully achieving the low-thermal-annealing ferroelectricity (LTAF) at 300 °C with $2{P}_{\text {r}}$ and endurance exceeding $38~\mu \text{C}$ /cm2 and $10^{{10}}$ cycles. The underlying mechanism of LTAF is attributed to the tetragonal ( ${t}{)}$ phase crystallization of HZO/ZrO2 stack at 300 °C with the help of ZrO2 as a ${t}$ -phase seed layer. This technique, ZrO2 IL, is expected to realize highly reliable ferroelectric device by utilizing the LTAF.