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A miniature planar meander-type slow-wave structure (SWS) for a W-band traveling-wave tube is studied. Computer simulation of the SWS electrodynamic parameters is performed. A new technology for fabrication of planar microstrip SWSs with the aid of laser ablation is proposed. The S-parameters of the SWS are experimentally studied. The experimental data are in good agreement with the results of the 3D computer simulation. Output characteristics of the traveling-wave tube with a sheet electron beam and planar SWS are calculated.

—The effect of low-dose γ radiation on the mechanisms of low-frequency conductivity of mesoporous silicon has been studied. It has been shown that γ irradiation preserves the hopping character of conductivity at a change of the frequency of phonon lattice vibrations, a decrease in the size of the hop, and a shift of the level of the capture of traps to the Fermi level in the band gap, which makes the structure with mesoporous silicon irradiated by γ radiation promising for the creation of multifunctional resistive and capacitive devices.

The possibility of modifying the photoluminescence properties of porous silicon by irradiation with low doses of γ photons from a 226Ra radioisotope source and bremsstrahlung is demonstrated. The position of the longest photoluminescence wavelength tends to shift to the short-wavelength region of the spectrum. The emission efficiency increases upon irradiation of both the substrate and the layer formed.

The influence of low doses of γ rays on the capacitive properties of structures based on mesoporous silicon has been investigated. The concentration distribution of dangling charged bonds over the layer depth, which changes under irradiation, has been found using the capacitance–voltage characteristics at different frequencies of the test signal. It is shown that the concentration and relaxation time of surface charged states in a structure with a mesoporous silicon layer decrease under γ irradiation, which makes the material promising for devices with controlled reactance (varactors) that are resistant to γ irradiation.

Electrical and photoelectric properties of porous silicon with introduced silver nanoparticles have been studied. It is shown that in the “dark–light–dark” operation mode, an abrupt jump of the dark current is observed upon illumination (with light spectrally close to sunlight), which is three to five times the initial dark current and the photocurrent. The voltages at which these abrupt changes in current are observed correspond to the range of existence of traps formed when the starting mesoporous silicon is obtained. It was found that the increased value of the dark current exhibits a long-term memory effect. The “current jump” can be attributed to the maximum capture of the generated photocarriers by traps, followed by their release in an electric field after the illumination.

A comparative study of the optical and morphological properties of different modifications of silicon and their dissolution upon interaction with distilled water and a biologically active medium is carried out. For the biologically active medium, nonpathogenic baker’s yeast (Saccharomycetes cereviseae) is chosen. It is shown that water and the biologically active medium interact with the surface of the materials and, thus, change the surface morphology and produce a modified layer. The strengths of the effect upon nanoparticles, nanoparticle-based structures (porous silicon), and single-crystal silicon doped with different types of impurities to different levels are different.

The effect of low exposure doses (5–40 kR) of gamma radiation on the electrical properties of structures based on a mesoporous silicon (SiMP) layer is investigated. It is demonstrated that the conductivity of the SiMP layer increases, the Fermi level shifts, and the trap density changes in gamma-irradiated Al/SiMP/p-Si/Al structures. Long-term stable switched-state memory in the region of the I–V curve hysteresis is revealed. This effect is controlled by the irradiation dose.

The photoelectric and photovoltaic properties of structures based on mesoporous silicon passivated with iron (SiMP:Fe) are studied. It is shown that these properties ambiguously depend on the iron concentration. In the case of a sample with space-charge-limited currents (SCLCs), the charge-transport mechanism in the Al-SiMP:Fe-p-Si-Al heterostructure changes under illumination from the SCLC type to the barrier type. Passivation with 0.1–0.2 at % iron stabilizes not only the electrical, but also the photoelectric and photovoltaic properties of the structures. A further increase in the Fe concentration gives rise to new traps caused by the appearance of iron and silicon oxides, which leads to instability of the properties. The structures exhibit high sensitivity under low-level illumination. The open-circuit voltage is 16 mV under AM-1 irradiation (∼2 mW/cm2).

The current-voltage and capacitance-voltage characteristics of structures based on mesoporous silicon, obtained by electroless etching with passivation by iron, (SiMP:Fe) are investigated. It is shown that the conductivity and barriers in Al-SiMP:Fe-p-Si-Al heterostructures ambiguously depend on the Fe concentration. Passivation by iron changes not only the conductivity of the SiMP:Fe layer but also the character of carrier transport at low frequencies. At an iron concentration of ∼1 at % tunneling transport through barriers becomes dominant in comparison with jumps over dangling bonds. Passivation of the SiMP layer by iron stabilizes the SiMP electrical properties (which is confirmed by the values of the trap concentrations estimated from the current-voltage characteristic) of structures subjected to long-term storage. This is likely to be related to the interaction between iron ions and the silicon surface with the formation of oxides.

The electrical and photoelectric properties of nanostructures with porous silicon layers obtained by electroless etching of silicon have been investigated. It is found that the photoelectric and photovoltaic properties of these structures depend on their morphology and are determined by not only the properties of the modified layer, but also the presence of possible barriers in the layered porous silicon. The ratio of the photoconductivity to the dark conductivity reached 102−5 × 102. An open-circuit voltage V oc was detected that amounted to ∼250 mV at an incident light power close to AM-1 (∼100 mW/cm2). In this case, the density of short-circuit current I sc was about 20 μA/cm2.

The possibility of multiparametric determination of properties of structures from the data on the dependence of reflectances Rp and Rs for polarized radiation and ratio Rp/Rs on the angle of incidence θ and from the angular dependence 1/Rp(ΔR/Δθ) is investigated. The results of natural and computer experiments revealed a high sensitivity of the angular dependence Rp(θ) of the reflectance to the values of optical constants and thickness of layered structures. Quantitative results of multiparametric measurements are verified by the independent method of spectral ellipsometry. The possibility of multiparametric determination of the properties and thickness of nanometer dielectric, metallic, and semiconducting layers on various substrates and the properties of substrates in such structures is established.