During the growth of float-zone and Czochralski crystals, the temperature distributions from the growth interface were measured using a two-colour infrared thermometer for the float-zone crystal surfaces and three thermocouples within the Czochralski bulk crystals. The results showed that the thermal gradient was a decreasing function of the growth rate, which forms the basis of this work. In a comparison of the shape variations in the growth interfaces observed in both float-zone and Czochralski crystals of three different diameters, all of the results were in agreement with the above premise. In consideration of Stefan's condition the premise above was discussed. One of the most important observations was that the region of increasing thermal gradient extends not only to the region grown before but also to the region afterward by stopping the pulling in float-zone crystals or lowering the growth rate in Czochralski crystals. This phenomenon was termed the “BA (before and after) effect”. The growing Czochralski crystals were detached from the melt and rapidly cooled so that the point defects were frozen. Using the anomalous oxygen precipitation phenomenon obtained by the above detaching, which demonstrated the existence of vacancies in the crystal, it was found that the growth interface was always filled with vacancies. By increasing the thermal gradient, which could be controlled by lowering the growth rate, the vacancy anomalous oxygen precipitation region was reduced, due to the generation of a silicon interstitial-rich region. The ratio of vacancies from the growth interface and silicon interstitials generated by the thermal gradient ultimately determines the nature of the bulk silicon crystal grown from the melt, i.e., with voids, defect-free or with dislocation loops.

Intrinsic Point Defect Behavior in Silicon Crystals During Growth from the Melt: a Model Derived from Experimental Results. T.Abe, T.Takahashi: Journal of Crystal Growth, 2011, 334[1], 16-36