Focus ion beam (FIB) lift-out was used to obtain cross-sectional (S)TEM samples using a Carl Zeiss Cross-Beam 1540 EsB system. The atomic structure and chemistry of the films were explored using high-resolution TEM (HRTEM), STEM high-angle annular dark field (STEM-HAADF) imaging and electron energy-loss spectroscopy (STEM-EELS) techniques. The Linköping double Cs corrected FEI Titan 3 60-300, operated at 300 kV, was used for this characterization. HRTEM images with bright-atom contrast were recorded under negative spherical aberration imaging (NCSI) conditions using slight positive defocus. STEM-HAADF imaging was performed by using a 21.5 mrad convergence semi-angle, which generates sub-Ångström resolution probes carrying ∼ 70 pA beam current. The STEM-HAADF images were recorded using an angular detection range of 46-200 mrad. STEM-EELS spectrum images, containing 43x96 pixels were acquired over a period of 6 minutes using energy dispersion of 0.5 eV per channel, a pixel dwell time of 0.1 seconds, and a collection semi-angle of 55 µrad using the embedded Gatan GIF Quantum ERS post-column imaging filter. Si, B, C, and O elemental distribution maps were extracted from the spectrum images by background subtraction, using a power law, and choosing characteristic edges for Si-K (110-143 eV), B-K (187-216 eV), C-K (285-311 eV). Fast Fourier transforms (FFTs) image analyses were carried out using the Gatan Microscopy Suite software. The measurements were repeated at multiple locations on the sample to ensure that they were representative. The Energy-dispersive X-ray (EDX) analysis generated spectrum images with a resolution of 256 x 256 pixels. These images were recorded for 4 minutes with a beam current of 0.4nA in the cumulative mode. A dwell time of 120μs was used per pixel by utilizing the embedded high solid angle Super-X EDX detector. From the STEM-EDX spectrum images, distribution maps of the elemental C, B, O, and Si were extracted and plotted using the Origin software.