Emergent ferroelectricity in subnanometer binary oxide films on silicon
Suraj Cheema, Nirmaan Shanker, Shang‐Lin Hsu, Yoonsoo Rho, Cheng‐Hsiang Hsu, Vladimir A. Stoica, Zhan Zhang, J. W. Freeland, Padraic Shafer, Costas P. Grigoropoulos, Jim Ciston, Sayeef Salahuddin
Abstract
The critical size limit of voltage-switchable electric dipoles has extensive implications for energy-efficient electronics, underlying the importance of ferroelectric order stabilized at reduced dimensionality. We report on the thickness-dependent antiferroelectric-to-ferroelectric phase transition in zirconium dioxide (ZrO 2 ) thin films on silicon. The emergent ferroelectricity and hysteretic polarization switching in ultrathin ZrO 2 , conventionally a paraelectric material, notably persists down to a film thickness of 5 angstroms, the fluorite-structure unit-cell size. This approach to exploit three-dimensional centrosymmetric materials deposited down to the two-dimensional thickness limit, particularly within this model fluorite-structure system that possesses unconventional ferroelectric size effects, offers substantial promise for electronics, demonstrated by proof-of-principle atomic-scale nonvolatile ferroelectric memory on silicon. Additionally, it is also indicative of hidden electronic phenomena that are achievable across a wide class of simple binary materials.