Blocking of dislocation propagation by faceted solid liquid interface during Ge crystal growth by the low thermal gradient Czochralski technique

The initial stage of germanium crystal growth by the low thermal gradient Czochralski technique of pulling from the melt (LTG CZ) has been studied in a series of experiments, in which the processes have been interrupted after pulling 6 mm in dia., 70–80 mm in length crystal rod and then up to 20 mm long a cone part. The axial gradients estimated from computer modelling were 2–2.5 K/cm. Crystals pulled in 〈1 1 1〉 direction with totally faceted interface were dislocation-free if facet formation was not disturbed. Crystals pulled along 〈1 0 0〉 under identical conditions, had rounded interface due to thermal roughens of (1 0 0) faces. In that case, the dislocation density was low, but not below ~10² cm⁻².