Analysis of the extended defects in 3C-SiC.pdf - Nelson Mandela ...

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2.6 Dislocations in the Zinc-Blende Structure
As in fcc metals, slip occurs in the zinc blende structure on close packed planes along
close packed directions. The predominant slip system is {111} with the
majority of dislocations lying along and directions.
The asymmetry in the zinc-blende lattice causes two possible dislocations in the
lattice for identical Burgers vector and dislocation line direction. As discussed earlier
the {111} layers consist of sets of closely spaced double layers of the constituent
atoms with small internal spacing
a 3a
and large external spacing of . The glide
4 3
4
of a dislocation can then either cut through the small internal spacing or large external
spacing. Two sets of dislocations are thus generated depending on the glide system.
The set of dislocations causing slip between the closest spaced layers is called the
glide set while the other called the shuffle set. The shuffle set is commonly assumed
to be the correct description since fewer bonds have to be broken for the dislocations
to move across the {111} planes.
The properties of dislocations in the zinc-blende structure may be explained in terms
of the concept of a 60° dislocation. In this configuration the slip plane is of the {111}
type with the dislocation line and Burgers vector making an angle of 60° with one
another. This is illustrated in Fig. 2.13.