Generation of Misfit Dislocations in Si1-xGex/Si Heterostructures

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Abstract
The mechanism for misfit dislocation generation in Si1-x Ge x /Si heterostructures is investigated by transmission electron microscopy. It is found that the dislocations nucleate at the surface, then expand to the interface by glide processes to generate 60°-type misfit dislocations. The nucleated dislocations are V-shaped with a 60° angle at the apex. One dislocation segment is of the above mentioned type, and the other is a screw-type. The V-shaped dislocation is energetically more favorable than the semicircular one. Existing surface atomic steps are shown to lower the activation energy of the dislocation generation.