Multiple Polarization States in Hf<sub>1−</sub><i><sub>x</sub></i>Zr<i><sub>x</sub></i>O<sub>2</sub> Thin Films by Ferroelectric and Antiferroelectric Coupling
Binjian Zeng, Lanyan Yin, Ruiping Liu, Changfan Ju, Qinghua Zhang, Zhibin Yang, Shuaizhi Zheng, Qiangxiang Peng, Qiong Yang, Yichun Zhou, Min Liao
Abstract
Abstract HfO 2 ‐based multi‐bit ferroelectric memory combines non‐volatility, speed, and energy efficiency, rendering it a promising technology for massive data storage and processing. However, some challenges remain, notably polarization variation, high operation voltage, and poor endurance performance. Here we show Hf 1− x Zr x O 2 ( x = 0.65 to 0.75) thin films grown through sequential atomic layer deposition (ALD) of HfO 2 and ZrO 2 exhibiting three‐step domain switching characteristic in the form of triple‐peak coercive electric field ( E C ) distribution. This long‐sought behavior shows nearly no changes even at up to 125 °C and after 1 × 10 8 electric field cycling. By combining the electrical characterizations and integrated differential phase‐contrast scanning transmission electron microscopy (iDPC‐STEM), we reveal that the triple‐peak E C distribution is driven by the coupling of ferroelectric switching and reversible antiferroelectric–ferroelectric transition. We further demonstrate the 3‐bit per cell operation of the Hf 1− x Zr x O 2 capacitors with excellent device‐to‐device variation and long data retention, by the full switching of individual peaks in the triple‐peak E C . The work represents a significant step in implementing reliable non‐volatile multi‐state ferroelectric devices.