Effect of Crystallization Front Shape on the Dislocation Density in Germanium Single Crystals

The effect of crystallization front shape on the dislocation density in Ge single crystals with a diameter of 100 mm, grown by the Czochralski method, has been studied. The dislocation density in crystals with a convex crystallization front is found to be considerably higher. The average dislocation density in experimental ingots with deviation of crystallization front shape from flat in the range from –1.5 to +1.5 mm increases from 75 to 1000 cm–2 and from 75 to 700 cm–2 in the cases of convex and concave fronts, respectively. Minimum dislocation densities are observed for a flat or slightly concave front.