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.

This paper presents a short description of a thin film parameter study technique based on the analysis of energy and angular spectra of ions backscattered from the film with initial energies in the 50–250 keV range, as well as on the registration of characteristic X-ray radiation induced in the film under study by the probing ion beam. The technique is a nondestructive one and makes it possible to determine the geometrical parameters of the film, the element composition and its change with depth, and the crystal structure quality of the film as a whole and of sublattices of definite elements. Some examples are given on the application of this technique to the study of multicomponent film structures at different stages of their growth.

Thin films of BaM hexaferrite (BaFe₁₂O₁₉) were grown on α-Al₂O₃(0001) substrates by laser molecular beam epitaxy. Structural, magnetic, and magneto-optical properties were studied using medium-energy ion scattering, energy dispersive X-ray spectroscopy, atomic force microscopy, X-ray diffraction, magneto-optical spectroscopy, and magnetometric techniques, and the dynamics of magnetization by ferromagnetic resonance method. It was shown that even a short time annealing drastically changes the structural and magnetic properties of films. Only annealed films demonstrate magnetic hysteresis loops in PMOKE and VSM experiments. The shape of hysteresis loops depends on thickness of films showing practically rectangular loops and high value of remnant magnetization (M_r/M_s~99%) for thin films (50 nm) and much broader and sloped loops in thick (350–500 nm) films. The magnitude of magnetization 4πM_s ≈ 4.3 kG in thin films corresponds to that in bulk BaM hexaferrite. Photon energy and sign of bands in magneto-optical spectra of thin films correspond to ones observed earlier in bulk samples and films of BaM hexaferrite. FMR spectra of 50 nm films at 50 GHz consist of a number of narrow lines. The width of main line ΔH~20 Oe is lower than has been reported up to now.

The initial stages in the growth of Ba_xSr_1−x TiO₃ films on various dielectric substrates were studied using the middle-energy ion scattering spectroscopy, and the results obtained were used to analyze microdefects in the film. The character of film growth was found to depend on the shape, size, and electrostatic state of crystallographic unit cells of the substrate surface. The growth was epitaxial on an SrTiO₃ substrate. The film prepared on an LaAlO₃ substrate consists of slightly disordered crystallites. Films on MgO substrates demonstrated island-type growth up to a thickness of 20 nm, with foreign phases observed to form; as the film thickness increased, the growth acquired an epitaxial pattern. The film grown on the $\alpha - Al_2 O_3 (1\bar 102)$ surface was polycrystalline and contained textured blocks.

(Sr,Ba)Nb₂O₆ (SBN) relaxor ferroelectric thin films exhibiting nonlinear properties promising for microwave applications were grown on a polycrystalline aluminum oxide substrate for the first time. Films of good crystallinity were obtained using the sputtering technique and high-temperature annealing. For all films, a significant change in the phase composition after high-temperature treatment was observed, and annealing provided a different effect on the phase composition of films deposited at different substrate temperatures. Tunable properties of the SBN films were investigated as a function of the deposition temperature and annealing conditions using planar capacitors with microwaves. The capacitor based on the strontium barium niobate film deposited at a temperature of 950 °C and subjected to annealing demonstrates a tunability of 44% and a loss tangent of 0.009 ÷ 0.022, which is expressed in the microwave commutation quality factor of 1740. This is the first successful attempt to form planar capacitive structures based on SBN films, which reveal a commutation quality factor above 1000 for tunable microwave applications.

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.