A robust Hf0.5Zr0.5O2 ferroelectric memory with high remanent polarization at 1 V and excellent stability up to 250 °C.

Abstract

The 5.5 nm Hf_0.5Zr_0.5O₂ (HZO) ferroelectric films exhibit a stable orthorhombic (o-) phase and outstanding memory performance near room temperature, achieving a remanent polarization (P_r) of 20.5 μC cm^-2 under a low operating voltage (V_rw) of 1 V. However, upon heating to 250-400 °C, most of the o-phase transforms into an antiferroelectric tetragonal (t-) phase. Conversely, a unidirectional voltage-pulse "wake-up" process can potentially promote the recovery of the t-phase back to the o-phase under high-temperature conditions; as a result, at 250 °C, P_r reaches 19.3 μC cm^-2 at V_rw = 1 V and 25.3 μC cm^-2 at V_rw = 1.5 V, with the corresponding endurance exceeding 10¹⁰ and 10⁹ cycles, respectively. Remarkably, most of the restored ferroelectric polarization can be well maintained even at elevated temperatures up to 350 °C. Notably, P_r remains ≥24.0 μC cm^-2 at V_rw = 1.5 V across the broad temperature range of 25-250 °C, even after ten complete thermal cycling steps (25 °C → 250 °C → 25 °C). This work establishes a robust materials foundation for high-density ferroelectric memories that simultaneously achieve high-temperature operational stability, low write voltage, superior endurance, and excellent retention.