## Results
### Characterization of the Grown WO\({}_{3}\) Films
It can be assumed that such particles act as nuclei for the formation of submicron spheres and ridges during hydrothermal film growth. Thus, the SEM results clearly demonstrate the complex nature of the microstructure of the grown film formed from both anisotropic structures (submicron ridges, elongated nanoparticles) and hierarchically organized submicron spheres. The absence of a clear texture and uniform microstructure may indicate that during the chosen hydrothermal treatment regime, mostly nucleation occurs (resulting in nanoparticles), with processes of further nuclei aggregation and Ostwald ripening (resulting in ridges and hierarchical submicron spheres) only in the initial stages. Such nonhomogeneous microstructure is also facilitated by amorphous substrate since, as can be seen below from the figure, the growth of the surface is more pronounced in the growth of the surface. Figure 4: Transmittance spectra of the studied samples in the visible range. Figure 3: XRD results (**a**) and Raman spectrum (**b**) for WO\({}_{3}\) film grown on glass substrate. the AFM results, the microstructure for film grown on the ITO layer (which is crystalline) differs significantly and is more uniform. The microstructure of the WO\({}_{3}\) film on glass is also consistent with its XRD results and Raman spectrum, which clearly indicate its high dispersity and X-ray amorphous nature. The surface of the formed film was also studied using X-ray elemental microanalysis, the results of which confirmed the formation of the WO\({}_{3}\) film and the absence of impurities not related to the substrate material. The microstructural features and local electrophysical properties of the formed oxide films were additionally studied using different AFM techniques. The results of the AFM study of the WO\({}_{3}\) film formed on the surface of the glass substrate are shown in Figure 6. The topographic scans show three types of formations constituting the film microstructure: ridges, individual 350-450 nm formations resembling submicron spheres of slightly distorted shape, and rounded nanoparticles between them. The latter evenly cover the area between the ridges and individual submicron formations, which is especially well seen in Figure 6c,e,f, and are mostly about 60 \(\pm\) 15 nm in size, although larger particles as big as 160 nm also occur. The ridges detected using AFM are 2-5 \(\upmu\)m long and widen toward the middle, reaching a maximum width of more than 1 \(\upmu\)m, and consist of elongated rods adjacent to each other (Figure 6c,e). The map of the surface potential distribution shows that there is some concentration of potential on the ridges themselves and nanoparticles between them, and on the contrary, at the edges of the ridges the potential is somewhat reduced. This indicates a shift in the density of charge carriers from the boundaries between the surface areas with different morphologies and the presence of homojunction at the ridge boundaries in contact with individual nanoparticles. At the same time, the difference in the potentials between the different surface areas mostly does not exceed 100 mV and indicates the presence of sufficient (although not high) conductivity of the material. Thus, the AFM data--both the topography and the surface potential distribution map--reliably indicate the continuous nature of the grown WO\({}_{3}\) film. Figure 5: Microstructure (SEM) of a WO\({}_{3}\) film grown on a glass substrate. The surface of the WO\({}_{3}\) film grown on the glass/ITO substrate was also studied using AFM. It can be seen that the film significantly differs in its microstructure from both the pure section of the substrate with an ITO layer and the WO\({}_{3}\) film on a glass substrate and consists of one-dimensional structures 350 \(\pm\) 25 nm long and 110 \(\pm\) 25 nm wide.