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.
A polarizing thin film Shrinking the footprint of electronics may require coming up with ferroelectrics that retain their properties down to nanometer-thickness films. Yang et al . add to a growing list of materials that retain ferroelectricity at these small length scales. The authors found a ferroelectric bismuth oxide structure that they stabilized with a small amount of samarium substitution. When coated on a substrate, the ferroelectric behavior persists down to one nanometer. The relatively high polarization makes these films good candidates for a variety of applications. —BG
A bismuth samarium oxide thin film on a substrate maintains its ferroelectricity at a thickness of only 1 nanometer.