Fig. 3: Phase structures (before and after fatigue).
From: Ultrahigh dielectric permittivity in Hf0.5Zr0.5O2 thin-film capacitors
a Low-magnification cross-sectional STEM-HAADF image of virgin HZO thin film (left panel). The framed yellow dashed rectangle is the oxygen vacancy penetration zone (~150 nm). The right-hand panel shows the simulated atomic structure for the [010]-Pca21 phase. b, c STEM-iDPC images of the O phases beyond and within the penetration zone framed in a, respectively. d, e Line scans over the rows of the oxygen columns framed in b, c, respectively. The dashed lines represent the intensities of the reference fully O-occupied columns, and the peak intensities that are lower than the reference line in e indicate the appearance of random oxygen vacancies at the O5 and O8 sites. f STEM-iDPC image of the [010]-oriented Pca21’ phase after fatigue. The inset in the top-left corner shows the simulation of this phase. g, h Two line scans of the atomic columns within the dashed rectangles framed in (f). Periodic changes in the oxygen intensities that deviate from the reference full-O dashed lines at the O2, O4 and O5 sites consistently implies the appearance of ordered oxygen vacancies when measured along two different \(([10\overline{1}]{{\rm{and}}}[\overline{1}0\overline{1}])\) directions.
