Czochralski-growth of germanium crystals containing high concentrations of oxygen impurities

Oxygen-containing germanium (Ge) single crystals with low density of grown-in dislocations were grown by the Czochralski (CZ) technique from a Ge melt, both with and without a covering by boron oxide (B 2O 3) liquid. Interstitially dissolved oxygen concentrations in the crystals were determined by the absorption peak at 855 cm −1 in the infrared absorption spectra at room temperature. It was found that oxygen concentration in a Ge crystal grown from melt partially or fully covered with B 2O 3 liquid was about 10 16 cm −3 and was almost the same as that in a Ge crystal grown without B 2O 3. Oxygen concentration in a Ge crystal was enhanced to be greater than 10 17 cm −3 by growing a crystal from a melt fully covered with B 2O 3; with the addition of germanium oxide powder, the maximum oxygen concentration achieved was 5.5×10 17 cm −3. The effective segregation coefficients of oxygen in the present Ge crystal growth were roughly estimated to be between 1.0 and 1.4.