Release Time:2019-11-04  Hits:

Indexed by: Journal Papers

Date of Publication: 2019-10-21

Journal: JOURNAL OF APPLIED PHYSICS

Included Journals: SCIE、EI

Volume: 126

Issue: 15

ISSN: 0021-8979

Abstract: Ferroelectricity in calcium doped hafnium oxide (Ca:HfO2) thin films has been experimentally proved for the first time in this work. All films prepared by chemical solution deposition exhibited smooth and crack-free surfaces, which were observed using an atomic force microscope. After 10(4) field cycling, a maximum remanent polarization of 10.5 mu C/cm(2) was achieved in HfO2 films with 4.8 mol. % Ca content. Meanwhile, the breakdown of the film occurred after 7 x 10(6) electric cycles. A phase transition from the monoclinic phase to cubic/orthorhombic phases was observed with increasing Ca concentration. We suggest the change in oxygen vacancy concentration as the origin of phase evolution, which was confirmed by X-ray photoelectron spectroscopy analysis. These results open a new pathway for realizing ferroelectricity in HfO2-based films. Published under license by AIP Publishing.