2026-08-06 ローレンス・バークレー国立研究所（LBNL）
Left: Cross-sectional electron microscopy image showing one-nanometer-thick titanium dioxide film grown on a silicon substrate and capped with platinum metal. Right: Schematic detailing titanium dioxide layers deposited on silicon. (Credit: Sayeef Salahuddin/Koushik Das/Berkeley Lab)
＜関連情報＞
- https://newscenter.lbl.gov/2026/08/06/ferroelectricity-emerges-at-the-nanoscale/
- https://www.science.org/doi/10.1126/science.aec9417
原子スケールの二酸化チタン誘電体膜における強誘電性 Ferroelectricity in atomic-scale titanium dioxide dielectric films
Koushik Das, Kate Reidy, Sajid Husain, Jong Ho Park, […] , and Sayeef Salahuddin
Science Published:5 Mar 2026
DOI:https://doi.org/10.1126/science.aec9417
Abstract
Ferroelectricity at atomic-scale thickness would have important applications in next-generation electronics. Here, we report that a ferroelectric phase can be stabilized in titanium dioxide (TiO2) films, a commonly known dielectric that is widely used in semiconductor technologies, by reducing thickness to <3 nanometers. Importantly, this ferroelectricity persists down to 1-nanometer thickness, approximately twice the unit-cell dimension. This thickness-dependent dielectric-to-ferroelectric phase transition demonstrates that an otherwise centrosymmetric, nonferroic fluorite-structure oxide can undergo structural inversion-symmetry breaking and exhibit voltage-switchable polarization. Atomic layer deposition–based low-temperature (<400°C) synthesis and the stability of this ferroelectricity on both silicon (Si) and amorphous surfaces [such as amorphous silicon dioxide (SiO2) and amorphous carbon films] demonstrate the feasibility of integration with a large variety of materials.
