Ferroelectricity in layered bismuth oxide down to 1 nanometer

TL;DR

This paper reports the development of a layered bismuth oxide film that maintains ferroelectricity down to 1 nanometer, promising for atomic-scale electronic devices.

Contribution

It introduces a novel layered bismuth oxide film stabilized by samarium bonding that exhibits ferroelectricity at atomic-scale thicknesses.

Findings

Ferroelectric hysteresis observed at ~1 nm thickness

Remanent polarization ranges from 17 to 50 μC/cm²

First-principles calculations confirm the ferroelectric nature

Abstract

Atomic-scale ferroelectrics are of great interest for high-density electronics, particularly field-effect transistors, low-power logic, and nonvolatile memories. We devised a film with a layered structure of bismuth oxide that can stabilize the ferroelectric state down to 1 nanometer through samarium bondage. This film can be grown on a variety of substrates with a cost-effective chemical solution deposition. We observed a standard ferroelectric hysteresis loop down to a thickness of ~1 nanometer. The thin films with thicknesses that range from 1 to 4.56 nanometers possess a relatively large remanent polarization from 17 to 50 microcoulombs per square centimeter. We verified the structure with first-principles calculations, which also pointed to the material being a lone pair-driven ferroelectric material. The structure design of the ultrathin ferroelectric films has great potential for the manufacturing of atomic-scale electronic devices.