Fig. 1: The observation of oxygen atoms of single orthorhombic (O-) phase grain in pristine TiN/Hf0.5Zr0.5O2 (HZO, 15 nm)/TiN device.

a Scanning transmission electron microscopy (STEM) high-angle annular dark-field (HAADF) image of the TiN/HZO/TiN cross-section. b Annular bright-field (ABF) image extracted from the green square area in a, in which the position of the O atomic columns can be clearly detected with different offset and direction. According to the O atomic columns deviated from the center of the four nearest Hf/Zr columns, it can be divided into OI type (center) and OII type (off-center). Some of the OII-site columns shift along the [001], while others shift to the opposite direction. c The atomic models of the Pbc21 and Pbca phases along [010] direction. The purple, navy blue, and cyan-colored solid balls correspond to the Hf/Zr, OI (center), and OII (off-center) ions, respectively.