On the switching dynamics of epitaxial ferroelectric CeO 2 -HfO 2 thin film capacitors

• Published in: Nano convergence Vol. 9; no. 1; p. 56
• Main Authors: Cüppers, Felix, Hirai, Koji, Funakubo, Hiroshi
• Format: Journal Article
• Language: English
• Published: England 14-12-2022
• ISSN: 2196-5404

Epitaxial layers of ferroelectric orthorhombic HfO
are frequently investigated as model systems for industrially more relevant polycrystalline films. The recent success in stabilizing the orthorhombic phase in the solid-solution cerium oxide - hafnium oxide system allows detailed investigations of external influences during fabrication. This report analyzes the ferroelectric properties of two thin film capacitors, which were post-deposition annealed in N
and O
atmospheres to achieve the orthorhombic phase after room temperature deposition. The samples, which exhibit very similar constituent phase, appear identical in conventional polarization-field hysteresis measurements. However, a significant switching speed difference is observed in pristine devices. Continued field cycling reduces the difference. Deeper analysis of switching transients based on the Nucleation Limited Switching model suggests that the O
heat treatment atmosphere results in an altered oxygen vacancy profile, which is reverted during ferroelectric cycling.