fig2
Figure 2. Microstructural and chemical analysis of electrode/HZO interfaces. Cross-sectional HRTEM images of the (A) Mo- and (B) 52MoN-based capacitors, respectively. These high-resolution images were used for precise IL thickness quantification to address the spatial resolution limitations of chemical mapping. The inset graphs in Figure 2A and B show representative depth-dependent HRTEM intensity profiles obtained by horizontal box-averaging; (C) Statistical analysis of the IL thicknesses extracted from 5 randomly selected regions across the full-span HRTEM images (see Supplementary Figure 5 for details). Based on this statistical extraction, the average IL thicknesses, determined by Gaussian fitting (FWHM), were estimated as 2.20 ± 0.21 nm for the Mo stack and 1.15 ± 0.07 nm for the 52MoN stack. Scanning transmission electron microscopy-energy-dispersive spectroscopy (STEM-EDS) elemental maps for the (D) pure Mo and (E) 52MoN stacks, showing Hf, Zr, O, Mo, and N distributions. The N map of the pure Mo stack is marked as 'Not Present in Pure Mo' because no nitrogen was introduced during the sputtering process of the pure Mo electrode. (F-J) EELS analysis; (F and G) show the HAADF image and O-K edge spectra for pure Mo, and H-J show the HAADF image, N-K edge, and O-K edge spectra for 52MoN, respectively. In Figure 2G, the green dashed circles mark the O-K edge features in the Mo electrode region, which signify interfacial Mo oxidation. In Figure 2I, the purple dashed circle marks the weak N-K edge signal within the HZO side near the bottom interface, providing evidence of nitrogen incorporation. In Figure 2J, the green dashed circles indicate the restricted O-K edge signals adjacent to the interfaces, thereby confirming the suppressed oxidation in the 52MoN stack. Line-scan colors correspond to the positions indicated in the HAADF images. IL: Interfacial layer; HZO: Hf0.5Zr0.5O2; HRTEM; high-resolution transmission electron microscopy; FWHM: full width at half maximum; EELS: electron energy-loss spectroscopy. HAADF: high-angle annular dark-field.
