Improvement of dopant distribution in radial direction of single crystals grown by micro-pulling-down method

Two iridium crucibles with one and five capillaries at a nozzle were developed for the growth of Ce-doped Y3Al5O12 [Ce: YAG] single crystals by the micro-pulling-down [mu-PD] method. The purpose of the study was to examine the effect of the capillary number on the Ce distribution in the radial direction of the crystals. The crystals grown from 2 mol% and 5 mol% Ce-doped YAG melts were then cut perpendicular to the growth direction and polished to produce specimens suitable for the measurement of Ce distribution. The Ce: YAG crystals grown using the crucible with one capillary [Ce: YAG(1 C)] had greater Ce content in the central portion of the crystal when compared to its peripheral parts. On the other hand, in the case of the Ce: YAG crystal grown using the crucible with five capillaries [Ce: YAG(5 C)], the increased Ce concentration was detected in five specimen sections positioned just below the capillaries. The results indicated that increase of the number of capillaries is effective practice that results in an improvement of the radial homogeneity of the single crystals grown by the mu-PD method.