Ferroelectricity in undoped hafnium oxide

Journal Article · Mon Jun 08 04:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4922272· OSTI ID:22412559

Polakowski, Patrick; Müller, Johannes ^[1]

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1. Fraunhofer Institute for Photonic Microsystems IPMS - Business Unit Center Nanoelectronic Technologies CNT, Dresden 01099 (Germany)

We report the observation of ferroelectric characteristics in undoped hafnium oxide thin films in a thickness range of 4–20 nm. The undoped films were fabricated using atomic layer deposition (ALD) and embedded into titanium nitride based metal-insulator-metal (MIM) capacitors for electrical evaluation. Structural as well as electrical evidence for the appearance of a ferroelectric phase in pure hafnium oxide was collected with respect to film thickness and thermal budget applied during titanium nitride electrode formation. Using grazing incidence X-Ray diffraction (GIXRD) analysis, we observed an enhanced suppression of the monoclinic phase fraction in favor of an orthorhombic, potentially, ferroelectric phase with decreasing thickness/grain size and for a titanium nitride electrode formation below crystallization temperature. The electrical presence of ferroelectricity was confirmed using polarization measurements. A remanent polarization P{sub r} of up to 10 μC cm{sup −2} as well as a read/write endurance of 1.6 × 10{sup 5} cycles was measured for the pure oxide. The experimental results reported here strongly support the intrinsic nature of the ferroelectric phase in hafnium oxide and expand its applicability beyond the doped systems.

• OSTI ID: 22412559
• Journal Information: Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 23 Vol. 106; ISSN APPLAB; ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CAPACITORS
FERROELECTRIC MATERIALS
HAFNIUM OXIDES
MONOCLINIC LATTICES
ORTHORHOMBIC LATTICES
THIN FILMS
TITANIUM NITRIDES
X-RAY DIFFRACTION