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This paper presents a technological study aimed at growing buried-channel heterostructures for single-mode semiconductor lasers operating in the spectral range 1600–1610 nm. We have produced laser diodes with an emission wavelength corresponding to an overtone in the absorption band of carbon dioxide and assessed the effect of temperature on their optical emission spectra. It has been shown that their emission spectra can be tuned over the range from 1559 to 1620 nm. We have demonstrated the feasibility of producing intelligent fiber-optic systems for remote carbon dioxide concentration monitoring. [ABSTRACT FROM AUTHOR]

Highly dispersed CaO has been synthesized by heating an aqueous solution of calcium nitrate and D-glucose up to 800°C. Calcium oxide is formed with an average particle size of 0.4 μm. According to X-ray powder diffraction and DSC studies, after exposure to the air for 24 h at 25°C the sample consists of crystalline phases of hydroxide (17.7 wt %), carbonate (20.0 %), calcium oxide (up to 5.5 wt %), and up to 56.8 wt % of the sample consist of a non-crystalline X-ray amorphous CaO phase. The synthesized highly dispersed CaO has been stored in the air at 25°C for 7 days. According to X-ray powder diffraction and DSC methods, the obtained sample consists of crystalline phases of calcium hydroxide (12.8 wt %) and calcium carbonate (83.4 wt %). The calculations error does not exceed 10%. [ABSTRACT FROM AUTHOR]

Comprehensive physical and technological studies on the creation of mesastripe structures with a channel in the substrate and subsequent burying of the structure with a layer of zinc selenide are carry out. Planarity of heterointerfaces between the substrate and epitaxial layers is studied by electron microscopy. The atomic structure of epitaxial layers GaInAsP/InP is studied by transmission electron microscopy. The profiles of epitaxial layers of the heterostructure are analyzed by secondary ion mass spectroscopy (SIMS). Layers with required composition of In0.78Ga0.22As0.68P0.32 corresponding to a laser wavelength of 1.3 μm are obtained. A technique for creating laser diodes with a channel in the substrate, including etching of mesastripe structure and burying with a layer of zinc selenide, is developed for the first time. This technique makes it possible to create laser diodes both with an optical confinement of laser emission and with a confinement of the current flow along the laser strip. Etching of p–n junction layers between laser strips and burying with zinc selenide on the surface of etched structure are developed for the first time. This technique made it possible to create heterostructures for laser diodes operating in the microwave range up to 10 GHz by liquid phase epitaxy (LPE). The ability to create and operate laser diodes in this design and technology is shown. The current–voltage characteristics, watt–ampere characteristics, and spectral characteristics of laser diodes are investigated. Russian technology for the creation of a microwave laser diode on a heterostructure with a channel in the substrate and repeated burying with zinc selenide is proposed. The prospects of using laser diodes of mesastripe structure with a channel in the substrate and buried with a layer of zinc selenide to create fast-response devices are shown. [ABSTRACT FROM AUTHOR]

The effect of bulk radiative heat transfer during the growth of profiled sapphire crystals from the melt is studied by the numerical simulation method. The peculiarities in the structure of a lightguide flow in the crystal and in the melt, as well as the possibility of radiation instability of the interface, are considered. It is shown that overcooled regions with the size determined by the growth rate appear under the crystallization front. It is found that the use of a conical shaper ensures a more stable growth. [ABSTRACT FROM AUTHOR]

We have studied the growth of zinc selenide layers on flat and shaped indium phosphide surfaces. The growth rate of zinc selenide has been shown to depend on substrate orientation. It has been shown that the present results can be useful in designing mesa stripe structures for quantum electronic instruments. We have fabricated mesa stripe laser diodes operating on the absorption band of methane and suitable for producing fiber-optic signal transmission systems. [ABSTRACT FROM AUTHOR]

This paper presents an analytical review that addresses physicochemical principles underlying the synthesis of granular structures in semiconductor–ferromagnet systems. Such systems comprise a II–IV–V2, II2–V3, or II–V2 compound as a semiconductor and MnAs as a ferromagnet. We demonstrate that granular magnetic structures are an alternative to superlattices in spintronic devices and can exhibit giant magnetoresistance and tunneling magnetoresistance effects. It is shown that, owing to the high carrier mobility in semiconductors, they are more attractive as matrices of granular materials than are metals or dielectrics. We have formulated the basic principles underlying the synthesis of granular structures with high magnetoresistance based on eutectic systems. Eutectic crystallization involves simultaneous crystallization of all the constituent phases, leading to the formation of an unusual, fine structure. High cooling rates are favorable for metastable crystallization. This causes a synergistic effect, stimulating nanostructuring and favoring the formation of granular structures. We present results on semiconductor–ferromagnet systems and demonstrate the possibility of producing granular magnetic structures with high magnetoresistance in such systems. [ABSTRACT FROM AUTHOR]

The new compound Аl2(SO4)3 ⋅ 8(CH3)2SO, which cannot be prepared by direct synthesis, has been synthesized from an Аl2(SO4)3 ⋅ 8(CH3)2SO ⋅ 3Н2О glass. The compound has been identified by X-ray diffraction. Based on IR spectra, it has been concluded that the Al3+ ion has mixed coordination to dimethylsulfoxide (DMSO) molecules, and the ligands are linked to each other through the S and O atoms. [ABSTRACT FROM AUTHOR]

We have studied the interaction of etchants and etchant mixtures with {100} planes of InP substrates. The results demonstrate that mesa stripes and grooves faceted by a combination of planes differing in polarity—{111}A, {111}B, {110}, {112}A, or {221}A—can be obtained by properly selecting the etchant and the orientation of the mask coating. The mesa stripes have been shown to be faceted by the most close-packed planes and, in the case of polar properties, they are faceted by planes with a low dissolution rate ({111}A for the sphalerite lattice). The most close-packed planes {111}A and {111}B differ in their orientation relative to the (110) and ( 10) basal planes. [ABSTRACT FROM AUTHOR]