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The effect of a traveling magnetic field on the parameters of Te-doped GaAs single crystals in the carrier density range of 5 × 1017–2 × 1018 cm‒3 has been studied. A traveling magnetic field was induced in a melt by a graphite inductor located in the setup chamber around the main heater. It is shown that a high-frequency magnetic field slightly reduces the dislocation density in the crystals without changing the shape of the dislocation distribution over their cross sections. The magnetic field affects the impurity distribution along the crystal axis, almost doubling the distance between the striation bands from 9 µm in the absence of magnetic field to 17 µm in a field with a frequency of 300 Hz. [ABSTRACT FROM AUTHOR]

Indium arsenide (InAs) single crystals heavily doped with Sn are found to have various violations of structural perfection, which depend on the Sn concentration in different regions of crystal. At low charge-carrier (electron) concentrations (~1.5 × 1018 cm–3) an unusual annular distribution of dislocations in the cross section is observed for the initial parts of crystal. The dislocation density lies in the range of (0.1–1.0) × 104 cm–2. At a carrier concentration above 4.0 × 1018 cm–3 indium inclusions and "vicinal growth hillocks" are observed in the final parts of crystals. The dislocation density in the final cross sections of crystals, in which the aforementioned defects are not observed, is in the range of (0.4–2.1) × 104 cm–2. [ABSTRACT FROM AUTHOR]

Facets are formed at the periphery of the conical part of GaAs single crystals grown by the Czochralski method when the melt is supercooled at the crystal periphery. The stronger the supercooling, the longer the facets are. A difference is observed in the facet shape between Sn- and Te-doped crystals. It is shown that the facet region is faceted by the А(111) plane. [ABSTRACT FROM AUTHOR]

The structural features induced by twinning in tin- and tellurium-doped gallium arsenide crystals during their growth by the Czochralski method with liquid melt sealing by boric anhydride have been considered. It is shown that growth twins and edge facets arise at the crystal periphery in the region of supercooled melt. The dopant concentration near a twin is always higher than in the region free of twins. A change is observed in the dislocation-growth direction in crystal during twinning. [ABSTRACT FROM AUTHOR]

The specific features of the formation of crystallites in gallium arsenide crystals grown by the Czochralski method have been investigated. The crystallites are found to have different shapes in the cross section and along the growth direction. It is shown that crystallites arise in the regions of flux supercooling under the peripheral region of crystal. [ABSTRACT FROM AUTHOR]

The influence of a dc magnetic field on the motion of growth dislocations with a density of (0.7–7.0) × 104 cm–2 and the electron density in the range of 5 × 1017–2.5 × 1018 cm–3 in Te-doped GaAs single crystals has been investigated. One experiment was performed with different magnetic field inductions (0.18, 0.33, and 0.50 T) and exposure time of 5 min. In another experiment the samples were subjected to a 0.50-T magnetic field for 3, 5, and 10 min. It is shown that the dislocations undergo the largest shift at the minimum magnetic field induction and the shortest treatment time. The maximum change in the electron density also occurs under these conditions. With the treatment time increase the dislocations tend to their initial positions and the electron density decreases. [ABSTRACT FROM AUTHOR]

The regularities of the defect formation in Si1 – xGex /Si heterostructures (x = 0.15 and 0.30), consisting of a low-temperature Si buffer layer and a SiGe solid solution, during their growth and subsequent annealings at temperatures 550–650°C are investigated by the methods of optical and transmission electron microscopy and X-ray diffraction. It is shown that the misfit-strain relaxation by plastic deformation under the conditions studied occurs most intensively in heterostructures with low-temperature SiGe buffer layers. The maximum degree of misfit-strain relaxation (no higher than 45%) is observed in the heterostructures with x = 0.30 after annealing at 650°C. The results obtained are explained by the effect of the nature and concentration of dislocation-nucleation centers, existing in low-temperature buffer layers, on the characteristics of the formation of a dislocation structure in the heterostructures under consideration. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

Comparative analysis of the specific features of the formation of a dislocation structure in the single-layer epitaxial heterostructures Si1 – xGex /Si and Ge1 – ySiy /Ge is performed. It is ascertained that, at a relatively low lattice mismatch between an epitaxial layer and a substrate, the sign of misfit strain at the interface significantly affects the processes of defect formation. The most probable reasons for the observed phenomena are analyzed with allowance for the specific features of the state of the ensemble of intrinsic point defects in epitaxial layers subjected to elastic strains of a different sign. © 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

Pseudomorphic Si[sub 0.76]Ge[sub 0.24]/Si heterostructures grown by molecular-beam epitaxy were irradiated with 350-keV Ge[sup +] ions at a temperature of 400°C so that the peak of the ions’ energy losses was located within the silicon substrate (deeper than the SiGe–Si interface). The effect of ion implantation on the relaxation of elastic stresses and the defect structure formed as a result of postimplantation annealing is studied. It is found that annealing at a temperature even as low as 600°C makes it possible to ensure a very high degree of relaxation of elastic stresses in the heterostructure and a comparatively low density of threading dislocations in the SiGe layer (<10[sup 5] cm[sup –2]). The results obtained make it possible to suggest a method for the formation of thin SiGe/Si layers that feature a high degree of relaxation, low density of threading dislocations, and a good surface morphology. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The photoluminescence spectra and behavior of the structural defects in layers obtained by implanting 1.0-1.8-MeV Er and Dy ions at a dose of 1 x 10[sup 13] cm[sup -2] are investigated after annealing at 1000-1200 °C for 0.5-1 h in argon or a chlorine-containing atmosphere. The structural defects are studied using transmission electron microscopy and selective chemical etching. The dominant features in the luminescence spectra of the Si:Er and Si:Dy layers following annealing in the chlorine-containing atmosphere are lines associated with the formation of edge dislocations, while the dominant features following the annealing of Si:Er and Si:Dy layers in argon are the erbium-related lines. A comparative analysis of the luminescence spectra of the Si:Er and Si:Dy layers shows that the highest intensity of dislocation-related luminescence is achieved in the erbium-implanted structures. A significant influence of intrinsic point defects on the structural and optical properties of erbium- and dysprosium-implanted silicon is revealed. [ABSTRACT FROM AUTHOR]