Multiple Polarization States in Hf<sub>1-</sub> <sub>x</sub>Zr<sub>x</sub>O<sub>2</sub> Thin Films by Ferroelectric and Antiferroelectric Coupling.
basic_science · Level V
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- Record sourced from PubMed, PMID 39713958.
- Also identified by DOI 10.1002/adma.202411463.
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Abstract
HfO<sub>2</sub>-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<sub>1-</sub> <sub>x</sub>Zr<sub>x</sub>O<sub>2</sub> (x = 0.65 to 0.75) thin films grown through sequential atomic layer deposition (ALD) of HfO<sub>2</sub> and ZrO<sub>2</sub> exhibiting three-step domain switching characteristic in the form of triple-peak coercive electric field (E<sub>C</sub>) distribution. This long-sought behavior shows nearly no changes even at up to 125 °C and after 1 × 10<sup>8</sup> 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<sub>C</sub> 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<sub>1-</sub> <sub>x</sub>Zr<sub>x</sub>O<sub>2</sub> capacitors with excellent device-to-device variation and long data retention, by the full switching of individual peaks in the triple-peak E<sub>C</sub>. The work represents a significant step in implementing reliable non-volatile multi-state ferroelectric devices.