Thin films of strontium titanate, which have nonlinear properties that are promising for microwave applications, were grown on a polycrystalline aluminum oxide substrate using magnetron sputtering and high-temperature annealing. It was shown that the improvement of the film structure with an increase in the deposition temperature was clearly correlated with both an increase in nonlinearity and an improvement in the loss level. A capacitor based on an SrTiO₃ film deposited at a deposition temperature of 900 °C and subjected to annealing demonstrated a tunability of 46% with a loss tangent of 0.009–0.014 at a frequency of 2 GHz. This was the first successful attempt to form a planar SrTiO₃ capacitor on an alumina substrate, which exhibited a commutation quality factor of above 3000 in the microwave range.

In this study, the structural and microwave properties of BaTiZrO₃ films deposited on alumina substrate were investigated. The films were deposited by RF magnetron sputtering in Ar/O₂ ambient atmosphere. The research of the island films at the initial stages of the growth showed that the pyramidal type of growth prevails. It was demonstrated that as-deposited film is a BaZrTiO₃ solid solution with a deficiency of titanium compared to the target. The air annealing at temperatures of 1100–1200 °C leads to the formation of a well-formed crystalline solid solution of BaZr_0.3Ti_0.7O₃ with a predominant orientation (h00). The investigation of microwave parameters of the films fabricated at different conditions showed that the best performance with the tunability of 4.6 (78%), and the Q-factor of 18 to 40 at 2 GHz was achieved at annealing temperature of 1150 °C.

Thin films of strontium titanate, which reveal high structure quality and tunable properties prospective for microwave applications at room temperature, were grown on a semi-insulating silicon carbide substrate using magnetron sputtering for the first time. The films’ growth mechanisms were studied using medium-energy ion scattering, and the films’ structures were investigated using X-ray diffraction. The electrical characteristics of planar capacitors based on strontium titanate films were measured at a frequency of 2 GHz using a high-precision resonance technique. It is shown that the tendency to improve the crystalline structure of strontium titanate film with an increase in the substrate temperature is most pronounced for films deposited at elevated working gas pressure under low supersaturation conditions. Planar capacitors formed on the basis of oriented SrTiO₃ films on silicon carbide showed tunability n = 36%, with a loss tangent of 0.008–0.009 at a level of slow relaxation of capacitance, which is significantly lower than the data published currently regarding planar tunable ferroelectric elements. This is the first successful attempt to realize a planar SrTiO₃ capacitor on a silicon carbide substrate, which exhibits a commutation quality factor more than 2500 at microwaves.

Thin films of strontium titanate were grown on a polycrystalline aluminum oxide substrate using magnetron sputtering. These films exhibit high structural quality and nonlinear properties, which make them promising for microwave applications. Planar capacitors based on SrTiO₃ films demonstrated a tunability of 1.65 with a microwave Q-factor of at least 110 in the entire range of control voltages without deterioration of losses, and a slow capacitance relaxation level no more than 4%, which is significantly better than currently published data for planar ferroelectric elements. This is the first successful attempt to create a planar SrTiO₃ capacitor on an alumina, which demonstrates a commutation quality factor CQF of 3300 at microwaves.

A theoretical model is proposed that allows us to describe the processes of formation of the sputtered atom flow, transport of this flow in the target-substrate space and deposition of the substance onto the substrate during magnetron sputtering. The main difference between the presented model and the existing ones is the combined consideration of the spatial distribution of sputtered atoms and the temperature gradient in the working chamber during magnetron sputtering at high power. To verify the model, real technological parameters of deposition of metal films by magnetron sputtering were used, optimized to achieve a high film growth rate. The agreement between the calculated film thicknesses obtained as a result of modeling and the experimental data was no worse than 5% at discharge powers in the range of 100 – 700 W. Comparison of the experimental data with the simulation results showed that the model adequately describes the sputtering processes at high discharge powers and low pressures, in contrast to approaches that do not take into account the temperature gradient in the working space.