卷 51, 编号 1 (2017)

The diffusion of magnesium impurity in the temperature range T = 600–800°C in dislocation-free single-crystal silicon wafers of p-type conductivity is studied. The surface layer of the wafer doped with magnesium by the ion implantation technique serves as the diffusion source. Implantation is carried out at an ion energy of 150 keV at doses of 5 × 10¹⁴ and 2 × 10¹⁵ cm^–2. The diffusion coefficient of interstitial magnesium donor centers (D_i) is determined by measuring the depth of the p–n junction, which is formed in the sample due to annealing during the time t at a given T. As a result of the study, the dependence D_i(T) is found for the first time. The data show that the diffusion process occurs mainly by the interstitial mechanism.

The results of investigating natural samples of chalcopyrite mineral CuFeS₂ from massive oceanic sulfide ores of the Mid-Atlantic ridge by the ⁶³Cu nuclear magnetic resonance (NMR ⁶³Cu) in a local field at room temperature are presented. The significant width of the resonance lines found in the ⁶³Cu NMR spectrum directly testifies to a wide distribution of local magnetic and electric fields in the investigated chalcopyrite samples. This distribution can be the consequence of an appreciable deviation of the structure of the investigated chalcopyrite samples from the stoichiometric one. The obtained results show that the pulsed ⁶³Cu NMR can be an efficient method for studying the physical properties of deep-water polymetallic sulfides of the World Ocean.

Longitudinal electrostatic waves in the quantum electron–hole plasma of semiconductors are considered taking into account the degeneracy of electrons and holes and the exchange interaction. It is found in the framework of linear theory that the dispersion curve of longitudinal waves has two branches: plasmon and acoustic. An expression for the critical cutoff frequency for plasma oscillations and an expression for the speed of sound for acoustic vibrations are derived. It is shown that the plasma wave always exists in the form of a superposition of two components, characterized by different periods and wavelengths. Two nonlinear solutions are obtained within nonlinear theory: one in the form of a simple superposition of two tones and the other in the form of beats.

The atomic and electronic structure of four variants of Te-terminated CdTe(111)B–(2√3 × 4) orthogonal polar surface (ideal, relaxed, reconstructed, and reconstructed with subsequent relaxation) are calculated ab initio for the first time. The surface is modeled by a film composed of 12 atomic layers with a vacuum gap of ~16 Å in the layered superlattice approximation. To close Cd dangling bonds on the opposite side of the film, 24 fictitious hydrogen atoms with a charge of 1.5 electrons each are added. Ab initio calculations are performed using the Quantum Espresso program based on density functional theory. It is demonstrated that relaxation leads to splitting of the four upper layers. The band energy structures and total and layer-by-layer densities of electronic states for the four surface variants are calculated and analyzed.

The band structure of three-layer symmetric InAs/GaSb/InAs quantum wells confined between AlSb barriers is analyzed theoretically. It is shown that, depending on the thicknesses of the InAs and GaSb layers, a normal band structure, a gapless state with a Dirac cone at the center of the Brillouin zone, or inverted band structure (two-dimensional topological insulator) can be realized in this system. Measurements of the cyclotron resonance in structures with gapless band spectra carried out for different electron concentrations confirm the existence of massless Dirac fermions in InAs/GaSb/InAs quantum wells.

The oxidation of mesoporous silicon in a double-layer “macroporous silicon–mesoporous silicon” structure is studied. The morphology and dielectric properties of the buried insulating layer are investigated using electron microscopy, ellipsometry, and electrical measurements. Specific defects (so-called spikes) are revealed between the oxidized macropore walls in macroporous silicon and the oxidation crossing fronts in mesoporous silicon. It is found that, at an initial porosity of mesoporous silicon of 60%, three-stage thermal oxidation leads to the formation of buried silicon-dioxide layers with an electric-field breakdown strength of E_br ~ 10⁴–10⁵ V/cm. Multilayered “porous silicon-on-insulator” structures are shown to be promising for integrated chemical micro- and nanosensors.

The prospects of the fabrication of solar cells based on metal oxides (ZnO formed by the hydrothermal method) with a bulk heterojunction are considered. The results of synthesizing zinc-oxide nanorods on different seed layers are presented. The important role of seed-layer formation is noted. It is shown that the structure of nanorod arrays can be controlled using a surfactant. Faceted nanorods are obtained, which are promising for designing new-generation solar cells.

The experimental results and calculations of the efficiency of the energy conversion of Ni-63 β-radiation sources to electricity using silicon p–i–n diodes are presented. All calculations are performed taking into account the energy distribution of β-electrons. An expression for the converter open-circuit voltage is derived taking into account the distribution of high-energy electrons in the space-charge region of the p–i–n diode. Ways of optimizing the converter parameters by improving the technology of diodes and optimizing the emitter active layer and i-region thicknesses of the semiconductor converter are shown. The distribution of the conversion losses to the source and radiation detector and the losses to high-energy electron entry into the semiconductor is calculated. Experimental values of the conversion efficiency of 0.4–0.7% are in good agreement with the calculated parameters.

The practical application of microstructured anodes produced by the electrochemical etching of single-crystal silicon is limited by their cost. The proposed approach will make it possible to reduce the cost for several reasons: less stringent requirements to the quality of the initial material due to the replacement of n-Si with p-Si, the exclusion of operations that are aimed at the formation of nucleation centers, and the repeated use of a silicon substrate. The formation of random macropores in 10–20 Ω cm p-Si (100) in a 4% solution of hydrofluoric acid in dimethylformamide is studied and the role of chemical etching is revealed. The dependences on the current density are obtained for the etching rate, morphology of the porous layers, effective valence, pore density, and average pore diameter. The part played by chemical dissolution in the electrolyte is determined. A technology is developed for the deposition of 50-μ-thick porous layers. This technology combines successive detachments of several membranes from the same substrate and provides enhanced porosity (~70%). The electrochemical characteristics of anodes formed from these membranes are examined, and 120+ test cycles are performed in the mode with the charge capacity limited to 1000 mA h/g at a current of 0.2 A/g.

Metamorphic Ga_0.76In_0.24As heterostructures for photovoltaic converters are grown by the MOCVD (metal–organic chemical vapor deposition) technique. It is found that, due to the valence-band offset at the p-In_0.24Al_0.76As/p-In_0.24Ga_0.76As (wide-gap window/emitter) heterointerface, a potential barrier for holes arises as a result of a low carrier concentration in the wide-gap material. The use of an InAlGaAs solid solution with an Al content lower than 40% makes it possible to raise the hole concentration in the widegap window up ~9 × 10¹⁸ cm^–3 and completely remove the potential barrier, thereby reducing the series resistance of the device. The parameters of an GaInAs metamorphic buffer layer with a stepwise In content profile are calculated and its epitaxial growth conditions are optimized, which improves carrier collection from the n-GaInAs base region and provides a quantum efficiency of 83% at a wavelength of 1064 nm. Optimization of the metamorphic heterostructure of the photovoltaic converter results in that its conversion efficiency for laser light with a wavelength of 1064 nm is 38.5%.

Microcrystalline wire-like InGaN/GaN light-emitting diodes designed as core–shell structures 400–600 μm in length are grown by metal–organic vapor-phase epitaxy on sapphire and silicon substrates. The technology of the titanium-nanolayer-induced ultrafast growth of nanowire and microwire crystals is used. As a current is passed through the microcrystals, an electroluminescence signal is observed in the blue–green spectral region.

Nanoscale copper (I) oxide layers are formed by magnetron-assisted sputtering onto glassy and silicon substrates in an oxygen-free environment at room temperature, and the structural and optical properties of the layers are studied. It is shown that copper oxide formed on a silicon substrate exhibits a lower degree of disorder than that formed on a glassy substrate, which is supported by the observation of a higher intensity and a smaller half-width of reflections in the diffraction pattern. The highest intensity of reflections in the diffraction pattern is observed for Cu₂O films grown on silicon at a magnetron power of 150 W. The absorption and transmittance spectra of these Cu₂O films are in agreement with the well-known spectra of bulk crystals. In the Raman spectra of the films, phonons inherent in the crystal lattice of cubic Cu₂O crystals are identified.

The structural, optical, and energy properties of epitaxial Al_xGa_{1 – x}As:Mg/GaAs(100) heterostructures at different levels of doping with Mg are studied by high-resolution X-ray diffraction analysis and Raman and photoluminescence spectroscopies. It is shown that, by choosing the technological conditions of Al_xGa_1–xAs:Mg alloy production, it is possible to achieve not only different conductivity types, but also substantially different charge-carrier concentrations in an epitaxial film.

We examined and discussed the interaction of two halomethanes (mono-chloromethane (MCM), and mono-fluoromethane (MFM)) with B₁₂N₁₂ and B₁₂P₁₂ fullerene-like nanocages as semiconductor based on density functional theory (DFT). We calculated adsorption energies and followed the changes in the electronic structure of semiconductors upon adsorption of MCM and MFM. We found that the adsorption on the B₁₂N₁₂ nano-cluster is energetically more favorable compared to B₁₂P₁₂ nano-cluster. Also for both systems we found higher values of adsorption energy for MFM than for MCM. We found that upon adsorption of above-mentioned species on these two fullerene-like semiconductors, the HOMO–LUMO distributions and also the gap energy for each system did not change significantly, which correspond to the physisorption process. As a result, B₁₂N₁₂ is a more appropriate nano-cluster to be used as a selective sensor for halomethanes, especially for MFM.