Several (111)-oriented Ga-doped Ge crystals were grown in pyrolytic BN containers by using the Bridgman or detached-Bridgman growth techniques. Growth experiments in closed-bottom pyrolytic BN containers resulted in almost completely detached-grown crystals, because the gas pressure below the melt could build up to a higher pressure than that above the melt. In open-bottom tubes, the gas pressure above and below the melt was balanced during the experiment, and therefore no additional force supported the detachment. In this case, the crystals grew attached to the wall. Etch-pit density measurements in the axial growth direction revealed a strong improvement in crystal quality of detached-growth samples as compared with attached samples. Starting in the seed, with an etch-pit density of 6 x 103 to 8 x 103/cm2, it decreased continuously in the detached-growth crystals to some 200 to 500/cm2. No significant radial difference existed between the etch-pit densities at the edge and middle of these crystals. In attached-growth samples, the etch-pit density increased to between 2 x 104 and 4 x 104/cm2 near to the edge, and to 104/cm2 in the middle of the sample. The difference between the detached- and the attached-growth crystals, with respect to etch-pit density, was therefore about 2 orders of magnitude.

Defect Density Characterization of Detached-Grown Germanium Crystals. M.Schweizer, S.D.Cobb, M.P.Volz, J.Szoke, F.R.Szofran: Journal of Crystal Growth, 2002, 235[1-4], 161-6