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volume flaws

Usual values of a dislocation density in ingots make (0,6... 5,0) ∙104см ' 2. In some cases at cultivation in monocrystals there can be polycrystalline inserts (polycrystalline structure) and doubles (unitized structure).

Polycrystalline flaws in germanium are volume flaws which are characterised by major extent of the defective field exceeding a continuance of a lattice in all three spatial directions. Polycrystalline inserts are macroscopical infringement of structure of a crystal. They represent the field of the crystal formed by a considerable quantity of randomly oriented small monocrystals. The polycrystalline or unitized structure of crystals arises on a lateral surface of ingots from macroparticles of pollution (okisnye films, equipment particles etc. more often.).

Germanium crystals grew up on installation "Редмет-10" an expedient Chohralsky in the form of cylindrical ingots in vacuo in a graphite thermal knot agree item 2.1.1. The basic crystallographic orientation monokritallov was - (111), the diversion from orientation did not exceed l0. As initial raw materials used polikristaplichesky zonnoochishchennyj germanium.

Into monocrystals for examinations by a special processing method during cultivation entered polycrystalline inserts. Polycrystalline inserts were formed at an initial stage of process and incremented with ingot growth.

In the given part of operation allocation of dislocations on height and section of crystals in polikristalpicheskih the fields adjoining to was explored
To polycrystalline inserts and on removal from a polycrystalline part.

In drawing 3.1 patterns of sections of a monocrystal of germanium in diameter of 77 mm with polycrystallization insert are presented. Sections are chosen at various height from an initial (upper) part of a crystal and show magnification of the area of polycrystalline fields in process of crystal growth. Polycrystallization has arisen during the moment razrashchivanija a monocrystal and on the upper section () is presented concerning small field.

Drawing 3.1 Structure of sections of a monocrystal of germanium with polycrystalline insert, section on height: 3 mm; 30 mm;

70 mm; 100 mm

In drawing 3.2. Dependence of a relation of the areas of polycrystalline field to monocrystal from crystal height is shown.

The full transmutation of structure into the polycrystalline takes place at achievement by an ingot of the height equal 1,5... 1,8 diameters.

Drawing 3.2 - Dependence of a relation of the areas of polycrystalline field to monocrystal (S ∏

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A source: Ivanova Alexandra Ivanovna. Micromorphology of a surface and dislocation structure of large-sized optical crystals of germanium and paratellurita. The dissertation on competition of a scientific degree of the candidate of physical and mathematical sciences. Tver - 2015. 2015

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