Formation Of Dislocation Structure Research Articles

Formation of defects in the process of ion implantation into A3B5

Abstract Ion impurity implantation into gallium arsenide and post-implantation annealing are accompanied by the formation of dislocation structure due to: a) coagulation of point defects; b) prismatic punching during precipitation. Irradiation by indium antimonide is accompanied by a deviation from stoichiometry, the formation of pored structure and of dislocation structure at depths exceeding the penetration depth of the implanted ions.

Effect of doping on formation of dislocation structure in semiconductor crystals

Numerous experimental data on the effects of dopants on the properties of dislocations and on the formation of dislocation structure in semiconductor single crystals grown from the melt are analyzed on the basis of model concepts derived from the results obtained in recent years (primarily by the authors of the present communication). Effects of dopants on generation, motion, and multiplication of dislocations are discussed in the high temperature range ( T ≳ 0.7 T melt), for the strress level typical for crystal growth τ/ G ≲ (10 -5−10 -4), dislocation density not exceeding 10 4−10 5 cm -2, and dopant concentrations far from the solubility limit. Changes in the dislocation structure of crystals caused by the effects of dopants on the generation, motion, and multiplication of dislocations are discussed. It is demonstrated that the changes caused by doping in the dislocation structure of semiconductor crystals can be explained on the basis of the relationship obtained between the doping impurities and the dynamic properties of dislocations.

Effect of buffer layers on the dislocation structure of heteroepitaxial systems

AbstractTransmission electron microscopy (TEM) as well as X‐ray topography (XRT) and X‐ray diffractometry have been used for investigation of the structure of the LPE heteroepitaxial system In0.05Ga0.95As‐InyGa1−yAs1−xPx‐GaAs(111) A. A critical value of the lattice misfit has been shown to exist at the metallurgical boundary ((Δa/a)* ≈ 10−3) which results in the change of the film nucleation and growth mechanism as well as the change of misfit dislocations (MDs) generation mechanism. With (Δa/a)0 > (Δa/a)* the nucleation and growth mechanism is mixed: island growth at the first stages of growth and layer‐by‐layer growth at large thicknesses. MDs are created in an “island film” developing a non‐ordered dislocation network. The density of threading dislocations (Nd) is ∼ 108 cm−2. With (Δa/a)0 < (Δa/a)* there is layer‐by‐layer mechanism of film's nucleation and growth from the very first stages of crystallization. MDs are injected into continuous layer along the inclined slip planes {111}, thus forming a regular three‐dimensional grid of MDs. Nd is less than 106 cm−2 in the case. A model of dislocation structure formation in heterolayers has been proposed. Within the frame of this model the two critical values of phosphorus concentration in the quaternary melt have been quantitatively determined. These are corresponding to the change of MD generation mechanism. The expected values of Nd for (Δa/a)0 > (Δa/a)* and (Δa/a)0 < (Δa/a)* have been theoretically determined.

Experimental effects of helium on cavity formation during irradiation—a review

Abstract Cavity (void) formation and swelling in non-fissile materials during neutron irradiation and charged particle bombardments are reviewed. Helium is the most important inert gas and is primarily active as a cavity nucleant. It also enhances formation of dislocation structure. Preimplantation of helium overstimulates cavity nucleation and gives a different temperature response of swelling than when helium is coimplanted during the damage process. Helium affects, and is affected by, radiation-induced phase instability. Many of these effects are explainable in terms of cavity nucleation on submicroscopic critical size gas bubbles, and on the influence of the neutral sink strength of such bubbles. Titanium and zirconium resist cavity formation when vacancy loops are present.

Formation of dislocation structure in silicon layers on non‐orienting substrates

AbstractA dislocation structure of Si layers crystallized from a floating grain on quartz glass and mullite ceramics substrates has been investigated by transmission electron microscopy (TEM) including the high‐voltage one. The effect of the layer orientation on the crystallographic features of dislocation distribution and brittle fracture in Si‐SiO2 system has been considered. The dislocation structure is proved to form mainly at temperatures lower than 0.8 of absolute melting temperature (Tm) of Si. Dislocation sources are located inside the crystallizable layer, and they are dislocations appearing from grain as well as the dislocation bundles near the interface. The cross slip of screws plays an essential role in dislocation multiplication. The difference of thermal expansion coefficients of the layer and substrate determines the finite dislocation density near the interface and in the bulk of the layer.

Application of X‐ray diffraction topography for the study of Al single crystals plastically deformed at low temperatures

AbstractThe Lang method has been used to investigate regularities and peculiarities of formation of Al single crystal dislocation structure in various stages of the stress‐strain curve at 77.3 and 4.2°K up to high strains. The low temperature deformation of crystals has been found to cause a sharp localization of the deformation into slip bands that correspond to different glide systems. A comparison with metallography is added.

1056. Investigation of regularities of formation of dislocation structure in alkali haloide crystals of predetermined shape grown in solid cruclible by the Bridgman method: L A Maslova and S V Tsivinskiy,Izv AN SSSR Ser Fiz, 37 (11), 1973. 2353–2356 ( in Russian)

1056. Investigation of regularities of formation of dislocation structure in alkali haloide crystals of predetermined shape grown in solid cruclible by the Bridgman method: L A Maslova and S V Tsivinskiy,Izv AN SSSR Ser Fiz, 37 (11), 1973. 2353–2356 ( in Russian)

Influence of crystallization conditions on formation of dislocation structure of germanium homoepitaxial layers produced by gas-transport technique

The dislocation structure of Ge layers has been studied by X-ray topography. The configuration, type, and density of dislocation are found to depend on temperature and growth rate. It is suggested, that the mechanism of the dislocation generation is based on the interaction of the growth steps with local inhomogeneities on the surface. The peculiarities of the dislocation behaviour in the growing layers in dependencce on the deposition temperature are discussed. [Russian Text Ignored.]

1020. Formation of dislocation structure in germanium epitaxial films during growth from vapour phase: L N Aleksandrov et al,Ukr Fiz Zh, 16 (9), 1971, 1543–1547 ( in Russian)

1020. Formation of dislocation structure in germanium epitaxial films during growth from vapour phase: L N Aleksandrov et al,Ukr Fiz Zh, 16 (9), 1971, 1543–1547 ( in Russian)

The Role of Strain Rate in the Formation of Dislocation Structure and Its Influence on the Mechanical Properties of Aluminium

The relationship between mechanical properties and dislocation substructure in aluminium after deformation at different strain rates has been studied. It was established that increase in strain rate increases flow stress and decreases the cell size of the dislocation substructure. From measurements of the misorientation angle between subgrains it was possible to determine the dislocation density and to present it as a function of the strain rate (at constant strain). It was also found that the flow stress is related to the cell size by the Hall–Petch equation, and that the proportionality factor k in this equation is independent of the misorientation angle.