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Analytical expressions of temperature dependencies of magnitude–frequency and phase–frequency characteristics of a HTSC RLC parallel circuit are obtained, where the resistance and inductance are non-linearly depended on the optical signal modulated by the intensity. It is shown that the magnitude–frequency and phase–frequency characteristics of circuits can be controlled by choosing the parameters of the HTSC thin film and optical “pump”.

Noise characteristics of silicon carbide Schottky barrier field effect transistors (MESFET) are examined for the case of the operation in small-signal regime and the presence of deep impurity levels and electron traps in the band gap of the channel. A new model of calculations of noise is suggested. It is shown that the noise measure of the short channel MESFET can be decreased within certain high frequency range.

The current–voltage characteristics (CVCs), photosensitivity, diffusion, generation–recombination, low frequency noises and detectivity of the visible range 6H–SiC p + nn + -double-injection (DI) photodetectors are studied. The agreement between theoretical results and experimental data is shown.

In the present paper, it is shown that a porous silicon can be presented as a set of clusters of silicon atoms surrounded by SiO x , whereas the single crystalline silicon substrate can be considered as an infinite cluster. The formulae for the estimation of variable porosity of the material (including the value of critical porosity — the percolation threshold, after which the characteristic phenomena are expected in porous silicon) and the forbidden bandgap value of clusters are suggested as functions of sizes of nanocrystallites. A new fractal model of the pore creation on the surface of a material is also proposed. The cases of semi-spherical, conical (V-groove dielectric isolation technology) and cylindrical (U-groove dielectric isolation technology) are considered. Formulae for the formed surface area S , porosity p of the material as a function of the depth and fractal dimension are obtained.

We propose a novel structure for a gas-sensitive element based on the change in the conductivity of ultra-thin, quantum-size semiconductor film caused by scattering of free carriers with charged ions of gas particles adsorbed on the surface of the film. To find a contribution of such scattering to the mobility, we have found the potential of adsorbed ions taking into account the screening effect of two-dimensional electron gas and the shift of electron distribution in the quantum-size film under the influence of average electric field of adsorbed surface charges. The mobility dependence on adsorbed gas particle surface density is different for positive and negative ions.

We investigated physical processes in semiconductor gas sensors and, in particular, dependencies of the surface potential and concentration of charge carriers in the space charge region of a semiconductor on the gas pressure. Corresponding sub-linear dependencies of the concentration of charge carriers on the gas pressure of an adsorbed gas are obtained both for the case describing by usual Langmuirian kinetic equation and in the case when the gas adsorption leads to a reduction in the heat of the adsorption due to a charging of the semiconductor surface.

The optical transitions taking place between two-dimensional surface subbands and bulk bands of semiconductors are investigated. It is shown that such transitions lead to a creation either of free carriers in bulk bands and two-dimensional surface subbands, or of excitonic states coupled with two-dimensional subbands. The theoretical description of these processes is elaborated. The low-temperature photoluminescence spectra of the GaSe crystals are investigated and it is shown that a variation of the surface potential leads to the dissociation of excitons coupled with two-dimensional surface subbands. The probability of such dissociations is evaluated. It is shown that these dissociations can lead, in particular, to an increase in the efficiency of the solar energy conversion in hydrogen energy.