Perfection and homogeneity of space-grown GaSb:Te crystals

A Te-doped GaSb crystal grown by the method of directed crystallization under microgravitation has been studied by X-ray topography. It is shown that the structural perfection of the crystal part grown without contact with the ampule walls is substantially higher than the structural perfection of the crystals grown under terrestrial conditions. The distribution of a Te dopant in the crystal is studied by quantitative X-ray topography, and it is shown that, if the gap between the growing crystal and the ampule is small, the Marangoni convection in the melt can be less intense than the convection provided by residual microgravitation. The relation between the formation of a flat face on the crystallization front (faceting) and the formation of twins is also established.