Segregation in Crystal Growth under High Gravity on a Centrifuge: A Comparison between Experimental and Theoretical Results
Germanium crystals doped with gallium were grown by the gradient freeze technique on a centrifuge at different rotation rates and with different lengths of the centrifuge arm. The resulting dopant distributions of these crystals indicate that convection was reduced during growth at some certain rotation rates, resulting in an effective segregation coefficient closer to one than for normal growth conditions. The experimental results agree with the theoretical prediction of a modified segregation model using a special boundary layer (Ekman layer) that occurs on a centrifuge. The results with respect to the uniformity of the crystals grown under high gravity on a centrifuge are compared with results obtained under microgravity.
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