Dislocations and twins formed in zone melted recrystallized Si on SiO ₂

Abstract

The microstructure of encapsulated silicon films recrystallized by zone melting, in a graphite strip-heater oven, was investigated by transmission electron microscopy. In the case where the film crystallized with its surface parallel to the (100) plane the major defects were long arrays of dislocations. These defects have sources of slip dislocations at their beginning point, which is indicative of plastic deformation. In other crystallographic cases, especially where the surface of the film was parallel to the (110) plane, the major defects were twins of the {111} 〈112〉 mode, which are typical to deformation twinning in diamond crystals. Both results indicate that the growth occurs under compressive stress which exists in encapsulated silicon films during their recrystallization. It is proposed that the (100) case can best accommodate the deformation by providing the largest number of slip systems, therefore it is energetically favorable. In the (110) case the reduced number of slip systems gives rise to deformation by twinning.