An Aqueous Route to Oxygen-Deficient Wake-Up-Free La-Doped HfO<sub>2</sub> Ferroelectrics for Negative Capacitance Field Effect Transistors.
basic_science · Level V
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- Record sourced from PubMed, PMID 37772990.
- Also identified by DOI 10.1021/acsnano.3c04983.
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Abstract
The crucial role of nanocrystalline morphology in stabilizing the ferroelectric orthorhombic (o)-phase in doped-hafnia films is achieved via chemical solution deposition (CSD) by intentionally retaining carbonaceous impurities to inhibit grain growth. However, in the present study, large-grained (>100 nm) La-doped HfO<sub>2</sub> (HLO) films are grown directly on silicon by adopting engineered water-diluted precursors with a minimum carbonaceous load and excellent shelf life. The o-phase stabilization is accomplished through a well-distributed La dopant, which generates uniformly populated oxygen vacancies, eliminating the need for oxygen-scavenging electrodes. These oxygen-deficient HLOs show a maximum remnant polarization of 37.6 μC/cm<sup>2</sup> (2<i>P</i><sub>r</sub>) without wake-up and withstand large fields (>6.2 MV/cm). Furthermore, CSD-HLO in series with Al<sub>2</sub>O<sub>3</sub> improves switching of MOSFETs (with an amorphous oxide channel) based on the negative capacitance effect. Thus, uniformly distributed oxygen vacancies serve as a standalone factor in stabilizing the o-phase, enabling efficient wake-up-free ferroelectricity without the need for nanostructuring, capping stresses, or oxygen-reactive electrodes.