The structural and gas-sensitive properties of n-N SnO₂/κ(ε)-Ga₂O₃:Sn heterostructures were investigated in detail for the first time. The κ(ε)-Ga₂O₃:Sn and SnO₂ films were grown by the halide vapor phase epitaxy and the high-frequency magnetron sputtering, respectively. The gas sensor response and speed of operation of the structures under H₂ exposure exceeded the corresponding values of single κ(ε)-Ga₂O₃:Sn and SnO₂ films within the temperature range of 25–175 °C. Meanwhile, the investigated heterostructures demonstrated a low response to CO, NH₃, and CH₄ gases and a high response to NO₂, even at low concentrations of 100 ppm. The current responses of the SnO₂/κ(ε)-Ga₂O₃:Sn structure to 10⁴ ppm of H₂ and 100 ppm of NO₂ were 30–47 arb. un. and 3.7 arb. un., correspondingly, at a temperature of 125 °C. The increase in the sensitivity of heterostructures at low temperatures is explained by a rise of the electron concentration and a change of a microrelief of the SnO₂ film surface when depositing on κ(ε)-Ga₂O₃:Sn. The SnO₂/κ(ε)-Ga₂O₃:Sn heterostructures, having high gas sensitivity over a wide operating temperature range, can find application in various fields.

Pt/(100) β-Ga2O3 Schottky barrier diodes were fabricated using a plate cleaved from the crystal grown by Czochralski method. Their electroconductive and photoelectric characteristics were studied. The following values were obtained: the Schottky barrier height (1.69/1.62/1.74 eV), ideality coefficient (1.09/1.14), saturation current density (9.91 × 10–15 A/cm2), diode series resistance (7.98 kΩ), and net donor concentration [(1.8–2.4) × 1018 cm–3]. The diodes demonstrate a high rectification ratio of 1010 at an applied voltage of ± 1 V and a relatively low experimental value of the leakage current density ∼10–11 A/cm2. These structures are solar-blind and also capable of operating in self-powered mode. The diodes are highly sensitive to short-wave ultraviolet radiation with a wavelength λ ≤ 265 nm. The maximum values of responsivity (20.4 A/W), external quantum efficiency (1.2 × 104%), and detectivity (9.6 × 1015 Hz0.5 × cm × W–1) of diodes were registered under exposure to irradiation at λ = 210 nm and at applied voltage of −1 V. The responsivity and external quantum efficiency values in the self-powered operation mode were 12.3 A/W and 7.2 × 103%, respectively. The diodes showed low rise and decay times in self-powered operation mode for photodiode based on Ga2O3: 14 and 30 ms, respectively.

The effect of mechanical tension on the multifractal characteristics of the lateral surface of a Fe₇₇Ni₁Si₉B₁₃ amorphous alloy is studied by scanning tunneling microscopy (STM). It is established that, at small loads, the surface is smoothed out much as a crumpled sheet of paper is smoothed out under tension. With an increase in the load, there appears a tendency to the formation of a fractal structure on the surface.

The influence of isothermal annealing on the chemical composition, microstructure, and surface relief of ribbons of an amorphous Fe₇₇NiSi₉B₁₃ alloy was studied using Auger electron spectroscopy and transmission electron, atomic-force, and scanning tunneling microscopy. It is established that an annealing below the glass transition temperature results in a boron enrichment of the ribbon surface layer on the side of the ribbon that was not in contact with the roller during quenching. On both sides of a ribbon, islands of crystallized material 2–5 μm in size appear consisting of nano-and microcrystals of α-Fe on the roller-contacting side and of iron boride on the opposite side. The surface relief on the roller-contacting side of a ribbon and that on the opposite side are shown to differ in terms of their spectral and fractal characteristics after annealing. The effect of the chemical composition and excess free volume of the surface layer on the formation of islands of crystallized material and surface relief is discussed.