fig14

Figure 14. Oxygenation and deoxygenation of HZO and associated phase transformations. (A) STEM-iDPC images under increasing positive bias showing R-phase evolution of an HZO grain. (B) Out-of-plane displacement of V_O with external bias in the marked supercell (red box) with respect to the positions in (A). Negative values indicate displacement toward bottom electrode. V_O shows both in-plane and out-of-plane (toward bottom electrode) components (inset). (C) A new grain nucleates in the same region at +4 V, giving rise to a polycrystalline nature (FFT in inset). (D) Another region in HZO film back at 0 V showing the O- and M-phases. Note the change of orientation from [111] to [100]. (E) STEM-iDPC image of domains (mutually rotated by 180° about [111]) in R-phase, which is retained when poled at -3 V (imaged at 0 V). Scale bars: 1 nm in (A, C, E), 2 nm in (D). Interfaces between HZO and top and bottom LSMO are marked in orange^[30]. HZO: Hf_0.5Zr_0.5O₂; STEM-iDPC: scanning transmission electron microscopy-integrated differential phase contrast; LSMO: La_0.7Sr_0.3MnO₃.