Sulfur is a substance with an abnormal dependence of viscosity on temperature. An experimental setup was created to study the viscosity of sulfur at pressures up to 100 bar and temperatures up to 500 °C. To visualize the process of falling of a tungsten carbide ball located in molten sulfur, the proton radiography method was used. The experiment was carried out on a PRIOR-II proton microscope (Institute for Heavy Ion Research, GSI, Darmstadt, Germany). In this experiment, the operating mode of the SIS-18 accelerator with slow beam extraction was used for the first time for proton radiography. The viscosity of the sulfur melt was measured at a pressure of 90 bar and temperatures of 190—320 °C. It has been shown that the viscosity of sulfur is greatly influenced by impurities, including hydrogen sulfide, which appears in the molten sulfur at high temperatures.

The results of experimental studies on semiconductor heterostructures with InGaAs quantum wells $\mathbf{(} \mathbf{9 8 0}-\mathbf{9 9 5 n m}$) grown by selective MOCVD epitaxy are presented. It is shown that the wavelength of photoluminescence varies across the window and depends on the thickness of the waveguide layer.

We have developed a numerical model and analyzed the waveguide properties of III-V/SOI structures for the creation of injection laser sources at wavelengths ranging from 1260 to 1600 nm. We studied the transmission coefficients of hybrid laser modes propagating from III-V/SOI to SOI waveguide in a three-dimensional waveguide with variable dimensions. The model enables the three-dimensional waveguide design optimization.

The effect of ion energy in a focused ion beam in the range 12–30 keV on the formation depth of nonradiative recombination centers during etching of the Al0.18Ga0.82As/GaAs/Al0.18Ga0.82As double heterostructure has been studied. It is shown that an increase in the ion energy leads to an increase in the concentration and propagation depth of radiation defects. It was found that during etching of focused ion beam with ion energies above 15 keV, the depth of formation of radiation defects exceeds 900 nm, which does not correspond to the calculations in the Stopping and Range of Ions in Matter.

The thermophysical properties of shock-compressed porous iron oxide at pressures up to 1 TPa were determined for the first time. The results agree well with earlier static and dynamic measurements in the pressure range up to 0.2 TPa. An equation of state for the high-pressure phase of iron oxide was constructed and compared with data at high pressures and temperatures.

The transmittance coefficient of silicon samples exposed to radiation of intense shock waves in xenon is measured. Shock waves are generated using the energy of condensed explosives. The intensity of radiation transmission at a wavelength of 1500 nm is measured by pyrometric methods. A model of the process based on the appearance of an absorbing layer in silicon due to photoionization is proposed.

The effect of the active region design on the vertical far-field divergence is studied for high-power laser diodes based on asymmetric heterostructures with a 4-μm thick waveguide and active region designs based on single (SQW) and double (DQW) InGaAs quantum wells. It is shown that the number of quantum wells has a significant effect on the divergence determined by the angle with the 95

In this study, the brightness temperatures of silicon shock-compressed to a pressure of P = 68 GPa and the evolution of its temperature during unloading are measured. The measurements were carried out in the infrared range Δλ1 = 1.1–1.7 µm, in which silicon is optically transparent, and in the visible range Δλ2 = 0.32–1.06 µm. The isentropic unloading of shock-compressed silicon into a vacuum is accompanied by an anomalous increase in the observed temperature.

The shock compressibility of single-crystal silicon is experimentally studied in the pressure range of 280 to 510 GPa. Shock waves are created using Mach's explosive cumulative generators. The parameters of shock waves are determined by the impedance matching method, and single-crystal quartz is used as a ref-erence substance. The results agree well with the ab initio calculation results and with the data obtained using laser shock waves.

For the first time, a new ceramic “Ideal,” a diamond-silicon carbide composite obtained in the reaction-diffusion Turing process, which makes it possible to obtain materials with the optimal set of physical and mechanical properties, is studied. An elastic-brittle fracture related to the propagation of a shock wave in a two-component system is noted. The dynamic elastic limit, determined by the properties of silicon carbide, is found to be 13.4 GPa. Its dynamic elastic limit and spall strength in the region of the elastic deformation are measured. The impact compressibility of ceramics up to a pressure of 625 GPa is determined.

A heterostructure design aimed at a multiple increase of the l060nm laser output efficiency is proposed. To multiply the internal and external quantum efficiency, tunnel p-n junctions (T J) were placed in the waveguide. Designed and MOCVD-grown heterostructures including two TJs demonstrate. Fabricated laser diodes demonstrate a stable second-order mode operation and a slope efficiency of 2.4W / A.

Ridge-waveguide semiconductor lasers operating in CW up to 500 mW with one TE00 mode and up to 2 W with few TE modes at RT are demonstrated. Highly dense arrays with stable Gaussian lateral far field (10 emitters, $200\ \mu\mathrm{m}$ total aperture) are shown to demonstrate 5 W in CW and 25 W in pulsed mode at RT.

The effect of ion energy in a focused ion beam in the range 12−30 keV on the formation depth of nonradiative recombination centers during etching of the Al0.18Ga0.82As/GaAs/Al0.18Ga0.82As double heterostructure has been studied. It is shown that an increase in the ion energy leads to an increase in the concentration and propagation depth of radiation defects. It was found that during etching of focused ion beam with ion energies above 15 keV, the depth of formation of radiation defects exceeds 900 nm, which does not correspond to the calculations in the Stopping and Range of Ions in Matter.

Цель работы заключалась в исследовании влияния нового типа податливых подложек на основе сверхструктурного слоя (SL) AlGaAs и слоя протопористого кремния (proto-Si), сформированного на c-Si, на практическую реализацию и особенности эпитаксиального роста слоя GaAs в методе MOCVD. Впервые показано, что низкотемпературный рост эпитаксиальных пленок GaAs высокого кристаллического качества может быть реализован за счет использования податливых подложек SL/proto-Si. Введение SL в состав податливой подложки в дополнение к proto-Si позволяет нивелировать ряд негативных эффектов низкотемпературного роста, снизить уровень напряжений в эпитаксиальном слое, защитить от автолегирования атомами кремния, сократить число технологических операций по росту переходных буферных слоев, улучшить структурные и морфологические характеристики эпитаксиального слоя. Ключевые слова: GaAs, Si, por-Si, сверхструктурный слой.

Measurements of the brightness temperature and compressibility of a dense silicon plasma formed by powerful shock waves (SWs) passing through a single-crystal sample have been carried out. Plane SWs were created using an explosive technique: the traditional plane acceleration of a steel driver plate made it possible to obtain pressures in silicon up to 133 GPa, and the use of "Mach" cumulative generators realized the pressures up to 510 GPa. The shock Hugoniot of silicon was determined by the impedance matching with alpha-quartz as the reference. The intensity of emitted thermal radiation was measured in the infrared range lambda similar to 1.5 mu m, where silicon is optically transparent, and in the visible range of the spectrum. A significant (up to five times) understatement of the measured values of the brightness temperature in comparison with the values calculated by the equation of state was found. Taking into account the reflective properties of the SW in silicon does not lead to an agreement with the experiment. The estimates of relaxation processes behind the shock front suggest the presence of a zone of the establishment of ionization equilibrium with a width of similar to 10 mu m.

The purpose of the study is to investigate the effect of a new type of compliant substrates based on an AlGaAs superstructure layer (SL) and a protoporous Si (proto-Si) layer formed on a crystalline Si (c-Si) layer on the optical properties of an epitaxial GaAs layer grown by metal–organic chemical vapor deposition. It is for the first time shown that the low-temperature growth of high-quality epitaxial GaAs films can be conducted using SL/proto-Si compliant substrates. The introduction of a SL layer in addition to proto-Si into the composition of the compliant substrate makes it possible to mitigate a number of negative effects of low-temperature growth, to reduce the level of strains in the epitaxial layer, to protect it from self-doping with Si atoms, to reduce the number of technological operations of the growth of transition buffer layers, to improve the structural and morphological characteristics of the epitaxial layer, and to attain good optical characteristics of the layer. The GaAs/Si heterostructures are studied by Raman spectroscopy, photoluminescence measurements, and optical transmission–reflection spectroscopy. The data will serve as an important material for understanding the fundamentals of the physics and technology of integrated III–V/Si heterostructures and for facilitating their use in optoelectronic devices.

The purpose of the study is to investigate the effect of a new type of compliant substrate based on an AlGaAs superstructure layer (SL) and a protoporous Si (proto-Si) layer formed on a crystal Si (c-Si) layer on the practical implementation and specific features of the epitaxial growth of GaAs layers by metal–organic chemical vapor deposition. It is for the first time shown that the low-temperature growth of high-crystal-quality epitaxial GaAs films can be implemented due to the use of compliant SL/proto-Si substrates. The introduction of a SL into the composition of a compliant substrate in addition to proto-Si makes it possible to neutralize a number of negative effects of low-temperature growth, to reduce the level of stresses in the epitaxial layer, to protect it from self-doping with Si atoms, to reduce the number of technological operations of the growth of transition buffer layers, and to improve the structural and morphological characteristics of the epitaxial layer.

Целью работы являлось исследование влияния нового типа податливых подложек на основе сверхструктурного слоя (SL) AlGaAs и слоя протопористого кремния (proto-Si), сформированного на c-Si, на оптические свойства эпитаксиального слоя GaAs, выращенного методом МОС-гидридной эпитаксии. Впервые показано, что низкотемпературный рост высококачественных эпитаксиальных пленок GaAs может быть реализован за счет использования податливых подложек SL/proto-Si. Введение SL в состав податливой подложки в дополнение к proto-Si позволяет нивелировать ряд негативных эффектов низкотемпературного роста, снизить уровень напряжений в эпитаксиальном слое, защитить от автолегирования атомами кремния, сократить число технологических операций по росту переходных буферных слоев, улучшить структурные и морфологические характеристики эпитаксиального слоя, а также достичь хороших оптических характеристик слоя. Проведены исследования полученных гетероструктур GaAs/Si методами рамановской спектроскопии, фотолюминесценции, спектроскопии оптического пропускания-отражения. Полученные данные послужат важным материалом для понимания основ физики и технологии интегрированных гетероструктур AIIIBV/Si, способствуя их применению в устройствах оптоэлектроники. Ключевые слова: гетероструктура GaAs/Si, податливая подложка, proto-Si, сверхструктурный слой, рамановская спектроскопия, фотолюминесценция, оптические спектры

For the first time, an analysis of a series of laser heterostructures with different active-region designs and cavity parameters is performed to solve the problem of generating sub-ns pulses with different characteristics (duration and peak optical power). For the study, semiconductor lasers of a mesa-stripe design with an aperture width of 100 μm and current pulses with a pulse base from 1 ns to 3 ns and an amplitude up to 50 A were used. It is shown that the minimum pulse width of the first relaxation peak was 50 ps at a peak power of up to 3 W with a combination of such parameters as a single QW, an optical confinement factor of 1.23 % and a cavity length of 700 μm. The use of multiple quantum well heterostructures provided the generation of pulses with a peak power of up to 30 W and a pulse width of 100-200 ps.

A comparative analysis of two types of heterostructures (1) symmetric with a single-mode ultrathin waveguide (0.1 μm thick) and (2) asymmetric with a multimode ultra-wide waveguide (1.7 μm thick). In the case of heterostructure (2) the maximum CW optical power reached is 1.6 W at 25 degrees and 2 W at -8 degrees, while the maximum efficiency reached is 54 %. Under the pulsed pump for both types of heterostructures, there is a time domain of unstable lasing.