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Ge layers heavily doped by a donor impurity are formed by implanting a p-Ge single crystal by two-charge antimony ions (Sb⁺⁺) with the energy E = 80 keV and the dosage Phi = 10¹⁶ cm^{- 2} with subsequent pulsed annealing of the implanted Ge:Sb layer by powerful ion beams (C⁺, H⁺) of nanosecond duration in a liquid phase. The surface morphology and depth profiles of Sb, the crystalline structure of the layer, the concentration of electrically active atoms, and photoluminescence of the Ge:Sb layers are investigated. The data on the Sb depth distribution are compared with the computer simulation results and show good agreement. The obtained results indicate that a high degree of activation of the implanted mixture of Sb (up to 100 %) and an increase in the direct-gap photoluminescence in the heavily doped layer for 300 K with a peak at 0.77 eV

The structure and photoluminescence of synthesized perovskite crystals CH³NH³PbI³ (lead triiodide methylammonium) are investigated in a wide temperature range. As temperature rises to 130-140 K, there is a transition from a orthorhombic to tetragonal crystal lattice with a change in the band gap. An increase in the stationary photoluminescence intensity at room temperature under the influence of exciting radiation is revealed. A model explaining the observed growth of photoluminescence is proposed.

Terahertz emission spectra of the surface of silicon crystals with different types of conductivity upon excitation by femtosecond laser pulses at various temperatures were experimentally recorded. Observed features in the terahertz spectra of the a silicon surface correspond to the energy structure of the impurity centers determining the type of conductivity of the sample. Comparison is made with the results obtained in the case of deposition of gold nanoparticles on the semiconductor surface. The spectral features of the surface with the deposed nanoparticles are discussed using the terahertz re-emission mechanism in two-phonon absorption

This paper considers mechanophysical methods (shear under pressure and explosive loading) developed for producing high-density optical nanoceramics based on some oxide magnetic semiconductors and their optical properties. Advantages of the techniques are the ease of implementation, a combination nano grinding and compaction of the material in a single process, obtaining high-density (99 %) stable materials, and the absence of external impurity. It is shown that copper oxide nanoceramics can be used as solar energy absorber and iron-yttrium garnet nanoceramics as an optical element in electromagnetic radiation modulators.

A local spectral analysis of multicomponent semiconductor nanostructures was performed based on the giant Raman scattering by semiconductor nanostructures on the surface of an array of Au nanoclusters near the metallized needle of an atomic force microscope. In the gap between the metal nanoclusters and the needle, where a semiconductor nanostructure is located, there is a strong increase in the local electric field (hot spot), resulting in a dramatic amplification of the Raman scattering signal. Unprecedented amplification of the Raman scattering signal by two-dimensional (over 10⁸ for MoS₂) and zero-dimensional (10⁶ for CdSe nanocrystals) semiconductor nanostructures was achieved. The use of the method for mapping the Raman scattering of a multicomponent system of MoS₂ and CdSe made it possible to identify components with a spatial resolution far exceeding the diffraction limit

A method is proposed for determining the orientation of phospholipide molecules in planar structures from spectra of non-polarized Raman scattering. The method is based on the sensitivity of the intensity of lines of Raman scattering on oscillations of CH₂ groups to the orientation of phospholipide molecules. The validity of the method is illustrated on a planar specimen of a saturated phospholipide prepared by drying from a solution. It is demonstrated that it is convenient to use the method of principal components to analyze the spatial distribution of molecule orientations in the specimen

The paper presents the results of calculation and growth of AlGaN/AlN heteroepitaxial structures with Bragg mirrors for the blue-green spectral range corresponding to the maximum broadband luminescence of the AlGaN:Si layers by molecular beam epitaxy from ammonia. Structures with an active AlGaN: Si region located on one lower Bragg mirror for a wavelength of 510 nm and between two Bragg mirrors for a wavelength of 510 nm were grown. For both heteroepitaxial structures, selection of the radiation of the active layer in the given spectral range by the lower Bragg mirrors was demonstrated. It is shown that a large total thickness of the heterostructure with two Bragg mirrors leads to cracks and macroscopic defects on the surface of the heteroepitaxial structure

The absorption spectral characteristics of silicon dioxide films in the IR range (λ =8-14 mu m) were studied to determine the optimal absorber thickness in the matrix structure of Golay microcells in order to design highly sensitive IR radiation detectors. It is shown that the absorption spectrum of SiO₂ films deposited by electron-beam evaporation has a multipeak structure in the thickness range up to 2 mkm and differs from the known absorption spectra of bulk silicon dioxide, which is apparently due to rearrangements in the film stoichiometry at the initial stages of film formation. Experiments have shown that the integrated absorption in deposited films in a given spectral range is close to a linear dependence on thickness and an order of magnitude smaller than the value obtained by calculation based on literature data for bulk SiO₂

Charge carrier diffusion is simulated by the Monte Carlo method in a photosensitive film of cadmium - mercury - tellurium (CMT) based infrared photodetectors for determining the spatial resolution of these photodetectors. Calculation results for matrix and linear photodetectors with differently designed matrix photoelements, including configurations with isolating diodes, are given. The calculated data are compared with experimentally measured resolutions of real photodetectors

This paper presents finite-element mathematical models for the real and simplified telescope lenses of the Lira-B space experiment. The results of calculation of the mechanics of the lens upon exposure to various external loads, both static and dynamic, are given. The calculations were performed using the ANSYS software package. Three methods for determining the characteristics of lightweight structures of the lens parts, two of which are used in the calculations, are described. Comparison of the results obtained using the real and simplified (reduced) models indicates that the simplified model can be used for initial estimates. Moreover, using this model with reduced characteristics, it is easier to develop and generate a finite element mesh, and it requires significantly shorter computational time