Photoluminescence and Transmission Electron Microscopy Methods for Characterization of Super-Multiperiod A3B5 Quantum Well Structures

Semiconductors - Promising semiconductor devices, such as quantum-cascade lasers and similar to them heterostructures with multiple strongly-coupled quantum wells, may contain hundreds and even...     

Chloride epitaxy of β-Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> layers grown on <Emphasis Type="Italic">c</Emphasis>-sapphire substrates

The method of chloride epitaxy is employed to grow β-Ga₂O₃ epitaxial layers on a c-sapphire substrate. Purified dry air is used as the source of oxygen. The layers are studied using the methods of X-ray diffraction, optical microscopy, scanning electron microscopy, transmission electron microscopy, and micro-Raman spectroscopy. It is found that the growth plane of the layers is (\(\bar 2\)01), parallel to the substrate surface. The layers consist of separate large crystalline grains of three different in-plane orientations rotated relative to each other in the growth plane by 60°. Misorientation can be caused by the different symmetry of the substrate and the epitaxial layer.     

GaInAsSb/GaSb heterostructures grown in the spinodal decay region by liquid-phase epitaxy from Sb-enriched solution-melts

Nearly isoperiodic solitary Ga_1−x In_xAs_ySb_1−y /GaSb heterostructures, in which the composition of the solid solution should be found inside the region of spinodal decay (x⩽0.4), were grown by liquid-phase epitaxy from solution-melts enriched with antimony. On the basis of the results of a study of structural and luminescence properties of Ga_1−x In_xAs_ySb_1−y /GaSb heterostructures we have determined the main conditions ensuring reproducible growth of epitaxial layers, homogeneous in the composition of their solid solutions in the region where the existence of processes of spinodal and binodal decay have been theoretically predicted. It is shown that the magnitude and sign of the deformation which the layer undergoes during growth and also the thickness of the layer are the main factors influencing the properties of the growing GaInAsSb solid solutions in the spinodal-decay zone. Fiz. Tekh. Poluprovodn. 33, 1134–1136 (September 1999)     

Electrical characteristics and structural properties of ohmic contacts to p-type 4H-SiC epitaxial layers

Epitaxial films grown by low-temperature liquid phase epitaxy on p-type 4H-SiC were used as strongly doped subcontact layers for making low-resistance contacts to the p-type material. The layers had a bulk resistivity of ∼0.02 Ω · cm and an aluminum atom concentration of ∼1.5×10²⁰ cm⁻³. The absence of polytype inclusions and the distinct crystalline quality of the strongly doped subcontact layers was confirmed by x-ray diffraction methods. Ohmic contacts with resistivities less than 10⁻⁴ Ω · cm² were prepared by depositing and then annealing multilayer metal mixtures containing Al and Ti. The structural properties and energy characteristics of the resulting ohmic contacts are discussed. Fiz. Tekh. Poluprovodn. 33, 1334–1339 (November 1999)     

Redistribution of carbon in the deformation of steel with bainite and martensite structures

Recent years have been marked by considerable increase in the use of high-strength steel—especially martensitic and bainitic steel—for the manufacture of key industrial components and structures. The high strength depends on strain hardening of the steel. It is important to understand the strain hardening of steel of different structural classes with active plastic deformation, in order to ensure specified structural and phase states and mechanical properties. In the present work, by transmission electron-diffraction microscopy, the evolution of the structure, the phase composition, and the state of the defect substructure is compared for steel samples with martensite and bainite structure in active plastic deformation to failure. After austenitization at 950°C (1.5 h) and subsequent quenching in oil (for 38KhN3MFA steel) and cooling in air (for 30Kh2N2MFA steel), multiphase structure (α phase, γ phase, and cementite) based on packet martensite (38KhN3MFA steel) and lower bainite (30Kh2N2MFA steel) is formed. Quantitative results for the structural parameters of steel in plastic deformation permit analysis of the distribution of the carbon atoms in the structure of the deformed steel. The points of localization of carbon atoms in the martensite (quenched 38KhN3MFA steel) and bainite (air-cooled 30Kh2N2MFA steel) are identified. Deformation of the steel is found to be accompanied by the destruction of cementite particles. For quenched martensitic steel, the total quantity of carbon atoms in the solid solution based on α and γ iron is reduced, while their content at structural defects is increased. The redistribution of carbon atoms in the bainitic steel with increase in the strain involves the increase in the quantity of carbon atoms in the α iron, defects in the crystalline structure, and cementite at the intraphase boundaries; and the decrease in the content of carbon atoms in the cementite particles within the bainite plates and the γ iron.     

Problems and Prospects for the Development of Textile,Light and Chemical Industries for the Production of Textile Fibres

Fibre Chemistry - The objective of the study is to substantiate the problems and prospects for the development of the textile, light and chemical industries of the Russian Federation for the...     

Method and Model for Enchancing Efficiency of Chemical Fiber Use in Textile Industry

Fibre Chemistry - A unique method for enhancing efficiency of chemical fiber use in textile industry based on a model of optimum selection of composition of blended fabrics is presented. The...     

Lasing wavelength of quantum dot heterostructures controlled within the 1.3–0.85 μm range by means of high-temperature annealing

We have studied the effect of high-temperature annealing on the properties of a laser heterostructure with InAs quantum dots in AlAs/GaAs superlattice. By increasing the time of annealing at 700°C, it is possible to provide for a smooth variation of the lasing wavelength from 1290 to 916 nm at a constant threshold current density (250 A/cm² at T ₀=110 K). By annealing the structure at 750°C, the lasing wavelength can be reduced to 845 nm.     

Adsorption-desorption processes on the surfaces of a hollow filament

Conclusions The processes of adsorption and desorption of diethanolamine on the surface of hollow polyphenylene phthalamide fibre, from baths of various concentrations, have been studied.It has been found that the adsorption process is not accompanied by chemisorption and has a reversible character, which makes it possible to completely wash out diethanolamine from the fibre surface. Toxicological studies have demonstrated the harmlessness of the washed hollow filaments.Translated from Khimicheskie Volokna, No. 6, p. 28, November–December, 1984.