Dendrite growth processes of silicon and germanium from highly undercooledmelts

The crystal growth behavior of a semiconductor from a very highly undercool ed melt is expected to be different from that of a metal. In the present ex periment, highly pure undoped Si and Ge were undercooled by an electromagne tic levitation method, and their crystal growth velocities (V) were measure d as a function of undercooling (Delta T). The value of V increased with De lta T, and V = 26 m/s was observed at Delta T = 260 K for Si. This result c orresponds well with the predicted value based on the dendrite growth theor y. The growth behaviors of Si and Ge were found to be thermally controlled in the measured range of undercooling. The microstructures of samples solid ified from undercooled liquid were investigated, and the amount of dendrite s immediately after recalescence increased with undercooling; The dendrite growth was also observed by a high-speed camera.