Investigation of the dislocation structure in Czochralski germanium crystals grown in [211] and [110] growth directions

The dislocation structure of single-crystalline germanium crystals grown by the Czochralski method in [2 1 1] and [1 1 0] directions has been examined by white beam X-ray topography. The dislocation densities in different parts of the crystals ranged from around 40 to 4000 cm−2. It was demonstrated that utilizing a well-executed Dash necking procedure with high growth speeds in growth directions parallel to a dislocation glide plane leads to the selection of dislocation line and type. Dislocations in the [2 1 1] crystal were mainly oriented in the [1 0 1] and [1 1 0] directions and hence confined within the ( 1 1) glide plane. A comprehensive Burgers vector analysis revealed that they were predominantly screw dislocations. The dislocation lines in the [1 1 0] crystal were mostly aligned to the [0 1 ], [1 0 ], and [1 0 1] orientations, within the ( 1 1) and (11) glide planes and predominantly 60° dislocations.