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The gallium distribution in nine germanium single crystals, all grown with similar heat conditions using the floating zone (FZ) method aboard five unmanned “Photon” spacecrafts (SC), from melts doped from 1×10 18 to 1×10 20 at/cm 3 are studied. For the first time, the strong anomalous concentration dependence of the distribution coefficient (from 0.16 to 0.089, respectively), having no “earth” analogue, was revealed experimentally as a result of comparative studies of space-grown and reference crystals. It also was shown, that the revealed dependence can completely define the longitudinal dopant distribution profile in a single crystal. The hypothesis of the nature of the observed effect was proposed, which consists of an intensification of the mixing processes in the heavily doped molten zone, restricted by free surface, caused by an increase of the surface-active impurity content in reduced gravity. |
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