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The results of investigation of photostimulated current switching during irradiation of mesoscopic structures based on Ge quantum dots in Si by weak infrared fluxes are presented. The small dimensions of the channel (approximately 70-200 nm) provide an opportunity to observe giant photoconductivity fluctuations which are due to the strong dependence of the hopping current on the filling of quantum dots by charge carriers. Replacing the silicon substrate with silicon-on-insulator made it possible to exclude the predominance of band conduction over hopping conduction at high temperatures and increase the photodetection temperature from 4.2 to approximately 100 K. The obtained results are the basis for the creation of a single-photon detector in a wide wavelength range.

The Raman scattering spectroscopy method is used to study the interaction of phonons and free charge carriers in doped semiconductor nanostructures (superlattices). In doped superlattices based on polar semiconductors, the collective vibrational modes of free charge carriers (plasmons) shield the long-range Coulomb interaction of cations and anions, which leads to the formation of mixed phononplasmon modes. The angular dispersion (anisotropy) of phonon-plasmon modes in doped GaAs/AlAs superlattices is studied. The observed anisotropy is due to the anisotropy of dielectric permeability in superlattices.

The dependence of the microwave insertion loss on the parameters of the heterostructure pin–diode is investigated by means of numerical modeling. The mechanisms of the emergence of this loss are determined, and the most influential mechanism is identified.

Spectral characteristics of metamaterials made of arrays of novel cylindrical resonators coupled with a substrate are simulated. It is shown that, apart from the usual modes, these resonators support additional modes due to a special shape of the resonators and to the presence of a dielectric substrate. In addition to the main resonance, the spectral characteristic has a resonance peak depending on the width of the transverse slit of the cylinder and the dielectric permittivity of the substrate. The dependences obtained in this work can be used to develop novel dynamically controlled metamaterials.

The evolution of the energy position of the maximum of the free exciton photoluminescence line in high-quality GaAs/AlGaAs heterostructures under optical excitation by short laser pulses of high density 5 · 10¹⁴–2 · 10¹⁸ cm⁻³ is considered. The influence of screening of the Coulomb interaction and interexciton exchange interaction are discussed. These effects give corrections to the exciton peak energy position of opposite signs. The second effect is sensitive to the exciton spin orientation and is manifested as splitting of the energy peaks of excitons with angular momentum projections +1 and −1. The value of splitting is proportional to the density of excitons and to the degree of their spin polarization and reaches 1.5 meV.

This paper presents a study of the effect of swift heavy Xe ions of energy 130-167 MeV at doses of 10¹²–10¹⁴ cm⁻² and Bi ions of 700 MeV at doses of 3 · 10¹²–3 · 10¹³ cm⁻² on films of stoichiometric thermal silicon dioxide, silicon dioxide films with ion-implanted excess silicon, and SiO_x films with the stoichiometric parameter x varying from 0 to 2. According to electron microscopy and Raman spectroscopy data, irradiation with the swift heavy ions resulted in the formation of silicon nanoclusters. The luminescence spectra depended on the size, number, and structure of the Si nanoclusters formed. Their size can be controlled by varying both the effect parameters (primarily, the ion energy loss per unit length of the track) and the stoichiometric composition of the films.

Conductive islands (quantum dots) of graphene and few-layer graphene in a fluorinated graphene matrix were produced by chemical functionalization of graphene in aqueous hydrofluoric acid. The structures formed were investigated by measuring the current-voltage characteristics and by means of an atomic-force microscope used to measure the surface topography and lateral forces. The presence of conductive islands in the fluorinated matrix was shown, and their sizes were determined.

The morphology and structure of CuS crystals formed during sulfidation of copper behenate films obtained by the Langmuir — Blodgett (LB) method have been studied using high resolution electron microscopy. The average size of these crystals is about 3 nm and increases by a factor of approximately 2.2 after annealing at a temperature of 150 ºC or above. Analysis of interplanar distances has shown that in the range of annealing temperatures of 150–200 ºC, CuS nanocrystals have a P6_3/mmc hexagonal crystal lattice with parameters a = 0.38 nm and c = 1.64 nm. At annealing temperatures of 250 ºC or above, the Cu₂S crystalline phase begins to form, in addition to CuS nanocrystals. The proportion of this phase increases with increasing annealing temperature. Cu₂S nanocrystals have a hexagonal crystal lattice type with the P6_3/mmc spatial group and unit cell parameters a = 0.39 nm and c = 0.68 nm. Quantitative evaluation of copper and sulfur in individual CuS and Cu₂S nanocrystals was performed by local analysis of characteristic X-ray spectra.

Current-voltage characteristics of thin dielectric films of HfO_x in p-Si/HfO_x /Ni structures are analyzed. Experimental results are compared with various theoretical models: the Poole-Frenkel trap ionization model, the multiphonon trap ionization model, and the Schottky effect at the Ni/HfO_x interface. It is shown that in spite of the good qualitative description of the experimental results by all models, only the multiphonon trap ionization model provides a quantitative description of the data.

This paper is devoted to the design and characterization of an electroosmotic pump based on asymmetric microchannel silicon membranes. A pronounced dependence of the pump flow rate on the structural asymmetry of microchannels was first found in experiments using deionized water. Pump flow rate was determined as a function of the applied voltage and the orientation of the matrix with respect to the volume of water pumped. An analytical description of the spatial structure of the microchannel matrices is proposed, which makes it possible to more accurately relate the structural and transport characteristics of the device. The data were used to calculate the zeta potential of the deionized water-silica-silicon system. It is assumed that the observed effect can be used as the basis for designing electroosmotic micropumps for modern bioanalytical micro- and nanofluidic systems.