Swirl Defects Research Articles

Characterization of swirl defects in floating-zone silicon crystals

The swirl defects in dislocation-free silicon crystals grown in argon atmosphere by the floating-zone method have been analysed by transmission electron microscopy. The 2 types of swirl defects consist of: (a) perfect dislocation loops for the type A swirl defect and (b) coherent or semicoherent precipitates for the type B swirl defects. Since both vacancy and interstitial dislocation loops are observed in the type A swirl defects it is concluded that their formation cannot adequately be described by previously developed nucleation models which were based on vacancy condensation only. It is possible that the aggregation of silicon self-interstitials has to be taken into account. It is also concluded from the observation of precipitates in the type B swirl defects that impurities may play an important role in determining the nature of the swirl defects.

TEM observation of dislocation loops correlated with individual swirl defects in as-grown silicon

Swirl defects in as-grown silicon single crystals could be observed directly in a transmission electron microscope after application of a special sample preparation method. Complicated dislocation loops were found at positions of individual swirl defects which had been revealed as hillocks rather than as etch pits by a modified Sirtl etch.