Generation and Propagation of Defects in Indium Antimonide

Abstract

Density of volume defects due to foreign particle inclusions in Czochralski= grown InSb crystals is 102-10~/cm a as detected by x-ray topography. The larger ones of these inclusions are frequently sources of dislocations. Dislocations in Czochralski-grown crystals are randomly oriented and curvilinear. InSb crystals prepared in space by partial remelting of Czochralski=grown seeds and regrowth after a 1 hr thermal soak period are markedly dii~erent. The density of inclusions is greatly reduced since foreign particles are accumulated during soak at the remelt boundary and at the melt surface. Dislocations originating from particles at the seed boundary are the cause of a sudden increase of dislocation density in the first portion of regrown material. Rectilinear dislocations (pure edge and 60 ~ type) are observed rather exclusively in the bulk of space-grown crystals. Since larger inclusions are.absent, few defects are generated, and the density of dislocations decreases along the axis of the samples due to outgrowing of rectilinear dislocations that are inclined to the growth axis. Increasing radial thermal gradients causes an increase of dislocation density in the crystal section solidified last. Generation and multiplication of dislocations due to radial thermal gradients become appreciable at gradients of about 10~176 ~Present address: Deutsche Forschungs-und Versuchsanstalt ffir Luft-und Raumfahrt,

Bulk Crystal Growth Under Microgravity Conditions

“…A major problem is concerned with the value of the residual gravity level, g, effectively acting on the fluid and consequently on the segregation. For example, in the case of the Skylab experiments, authors give values ranging from 10 −4 g 0 (Walter, 1977) to 10 −6 g 0 (Yue and Vottmer 1975). For Salyut, it is estimated to change between 5 × 10 −5 g 0 and 9 × 10 −7 g 0 , depending on the station attitude (Kashimov, 1979).…”

Crystal growth from melt in space

“…where the subscript a denotes solid and L is that region far away from the interface (taken to be the region which did not melt). It was found that k,, = 0" 12. k,tt is expected to be greater than the ratio /Co obtained at equilibrium which is 0.087 for Ga in ere (Walter 1977). The remari~ahle result is that k,n for the space-grown crystal is always larger than the earth-grown crystal.…”

“…Although the lach of tarring in some of the closed tube experiments showed that those experiments are essev~tially eontainerless we deal in this section speeitically with those experiments that were aimed o.t growing spherical crystals. These experiments were carried out by Walter (1976Walter ( , 1977. resolution differential etching Walter (1977) of a (lll)A section is shown in figure 16.…”

Solidification using a baffle in sealed ampoules: Ground-based experiments

“…Thus, by growing crystals in space, Ra is reduced to approximately 1, and the crystal growth process and its analysis are greatly simplified. Microgravity experiments with Te doped InSb the have been conducted on Skylab (1973) [6,7] and Salyut-6 (1978) [8] space stations, as well as on unmanned satellites Foton (1985,1986,1989) and Foton-3 (1987) [9]. The first study was carried out by Witt et al [6].…”