Lamellar growth phenomena in 〈111〉-oriented dislocation-free float-zoned silicon single crystals

An attempt was made to draw conclusions about elementary growth situations on the basis of typical doping inhomogeneities observed in dislocation-free float-zoned silicon crystals. Both nucleation and lamellar growth were equally recognized to be predominant factors in crystallization phenomena and discussed in terms of their influence on the speed of solidification. The incorporation of impurities and its changes initiated by such variations were treated separately for the case of thermal fluctuations (striations) and areas of preferential growth kinetics (facets). It is shown that, in the first case, the segregation theory of Burton et al., in the second case the incorporation model of Trainor and Bartlett can be applied. Increased dopant concentrations, as they were measured in “concave” regions of the solidification front could be explained as the result of an increased growth rate of lamellae in regions close to {111} planes.