The work examines the doping of a Si1 – xGex solid solution with donor (Sb, P) and acceptor (B) impurities during the synthesis process using electric pulse plasma sintering from powders with submicron particle sizes. The impurity content varied from 0.5 to 2.0 at

The kinetics of diffusion processes occurring during the formation of polycrystalline Si1 -xGex nanostructures (x = 0.20, 0.35) by spark plasma sintering in the temperature range 20-1200 degrees C was studied for the first time. A mechanism for the formation of a SiGe solid solution is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 mu m, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles.

The kinetics of diffusion processes occurring during the formation of polycrystalline Si1 – xGex nanostructures (x = 0.20, 0.35) by spark plasma sintering in the temperature range 20–1200°C was studied for the first time. A mechanism for the formation of a SiGe solid solution is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 µm, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles.

The magnetic properties and micromagnetic structure of [Co/Pt]10 multilayer magnetic films formed by independent variation of the Co and Pt layer thicknesses have been studied. The possibility of the film magnetization parameters manipulation was shown. It is found that the micromagnetic structure of the layers is significantly modified with a change in the thickness of the layers which correlates with the magnetization data. In particular, magnetic force microscopy revealed a system of magnetic skyrmions for a number of structures. The skyrmion density was found to be dependent on the growth conditions which in turn correlates with the shape of the magnetic hysteresis loop. Changing the thickness of the Co and Pt layers makes it possible to control the density of skyrmions in the range from 0.2 to 10.5 µm-2.

The properties of semiconductors are highly dependent on their crystalline structure. The formation of metastable polytypes under the action of external mechanical stresses leads to a change in the properties of the initial materials. In particular, for hexagonal silicon polytypes, an improvement in light-emitting properties can be observed compared to diamond-like silicon. In this work, the photoluminescent properties of silicon samples with the 9R-Si hexagonal phase synthesized by implanting Kr+ ions into the SiO2/Si system have been studied. The effect of post-implantation annealing conditions on the evolution of PL peaks in the spectral range around 1240 nm is analyzed. The contribution to the observed PL peaks of the light-emitting 9R-Si phase and W, S1, S2 defects associated with radiation damage in silicon substrates is discussed. It is shown that the formation of the 9R-Si phase and associated PL are affected by mechanical stresses formed in the SiO2 film upon irradiation.

The magnetic properties and micromagnetic structure of [Co/Pt] 10 multilayer magnetic films formed by independent variation of the Co and Pt layer thicknesses have been studied. The possibility of the film magnetization parameters manipulation was shown. It is found that the micromagnetic structure of the layers is significantly modified with a change in the thickness of the layers which correlates with the magnetization data. In particular, magnetic force microscopy revealed a system of magnetic skyrmions for a number of structures. The skyrmion density was found to be dependent on the growth conditions which in turn correlates with the shape of the magnetic hysteresis loop. Changing the thickness of the Co and Pt layers makes it possible to control the density of skyrmions in the range from 0.2 to 10.5 mkm -2 . Keywords: micromagnetic structure, skyrmions, CoPt films, electron beam evaporation.

Gallium oxide (Ga2O3) has recently attracted much attention due to the prospect of its application in power electronics and in other areas. An important task is the development of controlled and reproducible methods for doping this material with various impurities, among which boron is of considerable interest. The regularities of Ga2O3 doping with this isovalent (for Ga) impurity are poorly studied. Even for ion implantation as the most common semiconductor doping method these studies are still at the initial stage. In this work, the structural properties of β-Ga2O3 layers upon boron ion irradiation and subsequent annealing have been studied using X-ray Diffraction, Reflection High-Energy Electron Diffraction, Secondary Ion Mass Spectrometry, as well as theoretical calculations from first principles. Among the most interesting results are the establishment of a strong redistribution of implanted boron during post-implantation annealing and the conclusion about low degree of substitution of gallium sites by boron atoms.

In this paper, we propose a method for predicting the refractive index variation in InGaAlAs tunnel-coupled quantum wells under the action of an electric field. Complex of mathematical and experimental studies to optimize the heterosystems design forthe semiconductor modulator construction according to a planar Mach-Zehnder interferometer scheme is demonstrated.

In this paper, we propose a method for predicting the refractive index variation in InGaAlAs tunnel-coupled quantum wells under the action of an electric field. Complex of mathematical and experimental studies to optimize the heterosystems design forthe semiconductor modulator construction according to a planar Mach--Zehnder interferometer scheme is demonstrated. Keywords: Mach--Zehnder modulator, nanoheterostructure, quantum mechanical calculations, refractive index, transmission electron microscopy, photoelectric spectroscopy.

The kinetics of diffusion processes occurring during the formation of polycrystalline Si 1-x Ge x nanostructures (x=0.20, 0.35) by spark plasma sintering in the temperature range 20-1200 o C was studied for the first time. A mechanism for the formation of a SiGe solid solution is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 μm, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles. Keywords: spark plasma sintering, solid solution SiGe, thermoelectric characteristics, figure of merit ZT.

We report on the investigation of the growth defect formation in the GeSn/Ge/Si(001) epitaxial layers grown by hot wire chemical vapor deposition of Ge with simultaneous co-evaporation of Sn from an effusion cell. The nucleation of alpha-Sn nanoinclusions in the course of the growth process was found to be the main mechanism of elastic strain relaxation in the Ge1_xSnx epitaxial layers at x > 2.5% as opposed to the misfit dislocation formation at the GeSn/Ge interfaces. Also, beta-Sn nanoislands nucleating on the surface of the GeSn epitaxial layers with increased Sn concentration due to Sn segregation were identified by confocal Raman microscopy.

Synthesis and modification of gallium oxide as a wide-bandgap semiconductor is a topical task in the fields of power electronics, UV detectors, gas sensors, telecommunication. In the present work, the Ga2O3 films deposited on sapphire substrates by magnetron sputtering have been studied. The influence of deposition parameters and subsequent annealing on the structure and optical properties of the synthesized films is analyzed. Ion doping of magnetron-deposited films with silicon is carried out by the ion implantation method. It is shown by the Raman scattering and optical transmission spectroscopy that ion irradiation leads to the disordering of the crystal structure, but subsequent annealing results in a partial recovery of the structure. Hall-effect measurements for irradiated and then annealed films do not reveal the formation of a conducting layer. Apparently, this is due to the fact that the main contribution to the resistance is made by grain boundaries in the magnetron-deposited films.

The kinetics of diffusion processes occurring d0uring the formation of polycrystalline Si1-xGex nanostructures (x=0.20, 0.35) by electro-pulse plasma sintering in the temperature range 20-1200°C was studied for the first time. A mechanism for the formation of a solid solution of SiGe is proposed as a result of a comprehensive study of the microstructure and phase composition of samples with particle sizes from 150 nm to 100 μm, together with the analysis of experimental sintering maps. It is based on the phenomenon of mutual diffusion of Si and Ge atoms that occurs during the entire sintering process. For the selected sintering modes, the grain size of the formed SiGe corresponds to the size of the initial powder particles.

Thermoelectric Si 0,65 Ge 0,35 Sb δ materials have been fabricated by spark plasma sintering of Ge-Si-Sb powder mixture. The electronic properties of Si 0,65 Ge 0,35 Sb δ were found to be dependent on the uniformity of mixing of the components, which in turn is determined by the maximum heating temperature during solid-state sintering. Provided the concentration of donor Sb impurity is optimized the thermoelectric figure of merit for the investigated structures can be as high as 0.628 at the temperature of 490 °С, the latter value is comparable with world-known analogues obtained for Si 1- x Ge x P δ .

We report on growing the p-Ge:Ga/Si(0 0 1) epitaxial layers by hot wire chemical vapor deposition using a solid Ge:Ga sublimation source of Ga. The Ge:Ga layers grown using this doping method were featured by a high crystal quality and full electrical activation of the Ga impurity. The results of the present study demonstrate the prospects of application of the sublimation Ga source for growing the Ge:Ga layers in the Ge/Si(0 0 1) device structures for Si-based electronics and photonics.

The possibility of controlling the curvature of the profiles of the surface of X-ray optical elements using single-crystal SiO2(011) plates of rectangular and trapezoidal shapes was studied. In bending regulators (BRs) of various forms, the active element was a piezoelectric bimorph glued to a single-crystal plate. Experimental and calculated data of changes in the profile and radius of curvature of the surface of the used plate are given. The influence of the forms of the components of the bending regulator is shown on the initial profile and surface curvature of X-ray optical elements.

Spin light-emitting diodes based on InGaAs/GaAs heterostructures with a CoPt ferromagnetic injector were fabricated. It was demonstrated that the processing of these structures in selenium vapor prior to the deposition of a CoPt contact provides an opportunity to enhance the circular polarization degree of diode emission. The observed increase in the polarization degree is attributed to the suppression of spin relaxation at the metal/semiconductor interface due to surface passivation and a reduction in the density of surface electron states as a result of processing in selenium vapor.

AbstractSpin light-emitting diodes based on InGaAs/GaAs heterostructures with a CoPt ferromagnetic injector were fabricated. It was demonstrated that the processing of these structures in selenium vapor prior to the deposition of a CoPt contact provides an opportunity to enhance the circular polarization degree of diode emission. The observed increase in the polarization degree is attributed to the suppression of spin relaxation at the metal/semiconductor interface due to surface passivation and a reduction in the density of surface electron states as a result of processing in selenium vapor.

A bulk nanostructured material based on oxidized silicon nanopowder was fabricated using a spark plasma sintering technique. Structural investigations revealed that this material has the composition of ∼14 nm core Si granules inside an SiO2 shell. Photoluminescence measurements have shown that the emission spectra lie in the energy range of 0.6-1.1 eV, which is not typical of the emissions of the Si/SiO2 nanostructures reported in numerous papers. This result can be explained by the formation of energy states in the bandgap and the participation of these states in both electronic transport and photoluminescence emission. Annealing of the sample leads to a decrease in defect density, which in turn leads to quenching of the 0.6-1.1 eV photoluminescence. In this case ∼1.13 eV inter-band transitions in the Si core start to play a dominant role in radiative recombination. Thus, the possibility of controlling the photoluminescence emission over a broad wavelength range was demonstrated.