## 3 Results
The deposition of the BTS film in a gas medium containing 20% oxygen leads to the formation of (211) textured coating with the lattice parameter 4.09 A, which corresponds to the composition BaTi\({}_{0.28}\)Sn\({}_{0.72}\)O\({}_{3}\) solid solution. Figure 2 demonstrates diffractograms of BTS films deposited on alumina in the substrate temperature range of \(T_{\rm s}\) = 650-850 \({}^{\circ}\)C in a gas mixture of Ar (80%)/O\({}_{2}\) (20%). The dotted lines correspond to the positions of the reflexes for BaTi\({}_{0.8}\)Sn\({}_{0.2}\)O\({}_{3}\) sputtered target. It is seen that an increase in the deposition temperature leads to a change in the growth texture from (211) to (110), as well as to a shift of reflexes towards large angles, which indicates a decrease in the lattice parameter of films from 4.09 A till 4.07 A, and, hence, an increase in the concentration of barium titanate in a solid solution from 28% (BaTi\({}_{0.28}\)Sn\({}_{0.72}\)O\({}_{3}\)) to 40% (BaTi\({}_{0.4}\)Sn\({}_{0.6}\)O\({}_{3}\)), and an approach of the component composition of the film to the composition of the sputtered target (see the inset in Figure 2). At a temperature of 850 \({}^{\circ}\)C, the film solid solution reveals the pronounced preferential orientation (110). However, despite the positive trend of increasing the content of BaTiO\({}_{3}\) in solid solution with increasing \(T_{s}\), stoichiometric transfer of the target composition into the film by increasing the deposition temperature cannot be achieved. It can be assumed that secondary phases rich in titanium are still present in the films, the content of which decreases with an increase in the deposition temperature. Figure 3 shows the diffractograms of the above-described BTS films but subjected to high-temperature annealing in air at a temperature of 1100 \({}^{\circ}\)C for two hours. Post-growth high-temperature treatment radically changes the structural properties of the studied films. During annealing, titanium is redistributed between the secondary phases and the main phase of BTS, as a result of which the composition of the film solid solution after annealing repeats the composition of the BaSn\({}_{0.2}\)Ti\({}_{0.8}\)O\({}_{3}\) target with the lattice parameter 4.03 A (see inset with reflex (211) in Figure 3). In addition, for films deposited at \(T_{\rm s}\) = 650 and 700 \({}^{\circ}\)C, annealing leads to an increase in the intensity of the reflex (111), and for films grown at \(T_{\rm s}\) = 800 and 850 \({}^{\circ}\)C, to a decrease in the width of the dominant reflex (110), which indicates an improvement in the quality of the crystal lattice of the coatings under study. Figure 1: Diffractograms of the BTS thin films on Al\({}_{2}\)O\({}_{3}\) substrates deposited at different oxygen concentrations in gas ambient. Figure 4 shows the AFM images of the surface of the studied samples before and after annealing. The linear substrate defects typical for polycrystalline aluminum oxide are clearly visible in the image before annealing, indicating that the film repeats the morphology of the substrate. The grains dimension of the non-annealed sample is about 150-300 nm (Figure 4a) and the surface roughness is about 20-30 nm (Figure 4b). According to the Figure 4c, as a result of annealing, the structure of the film surface becomes finer grained, the grain dimensions decrease to 50-150 nm, the grain boundaries become more pronounced, and the surface roughness decreases to 10-15 nm (Figure 4d). Figure 3: Diffractograms of the BTS thin films on Al\({}_{2}\)O\({}_{3}\) substrates at different substrate temperatures after annealing at 1100 \({}^{\circ}\)C in air. Figure 2: Diffractograms of the BTS thin films on Al\({}_{2}\)O\({}_{3}\) substrates at different substrate temperatures. Planar capacitors are formed on the basis of BTS films deposited in a gas medium Ar(80%)/O\({}_{2}\)(20%) at different substrate temperatures.