On the switching dynamics of epitaxial ferroelectric CeO2–HfO2 thin film capacitors

• Published in: Nano convergence Vol. 9; no. 1; pp. 56 - 9
• Main Authors: Cüppers, Felix, Hirai, Koji, Funakubo, Hiroshi
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 14.12.2022; Springer Nature B.V; SpringerOpen
• Subjects: Capacitors; Cerium oxides; Chemistry and Materials Science; Communication; Cycles; Deposition; Electrodes; Epitaxial layers; Ferroelectric materials; Ferroelectricity; Fluorite Structure Ferroelectric Materials and Devices; Hafnium oxide; Heat treating; Heat treatment; Influence; Investigations; Iron constituents; Materials Science; Nanoscale Science and Technology; Nanotechnology; Nanotechnology and Microengineering; Nucleation; Orthorhombic phase; Room temperature; Solid solutions; Switching; Thin films
• ISSN: 2196-5404; 2196-5404
• DOI: 10.1186/s40580-022-00344-4

Epitaxial layers of ferroelectric orthorhombic HfO 2 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 2 and O 2 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 2 heat treatment atmosphere results in an altered oxygen vacancy profile, which is reverted during ferroelectric cycling.