A large angle convergent beam electron diffraction study of the core nature of dislocations in 3C-SiC

Dislocations produced by 1300 degrees C indentation of the silicon-terminated (111) face of 3C-SiC were investigated by transmission electron microscopy. They were all found to be either widely separated partial dislocation pairs, or else, arrays of single partial dislocation half-loops on neighboring parallel slip planes and having the same Burgers vector. It was concluded that in the latter case, each array consisted of leading partial dislocations which had nucleated without accompanying trailing partial dislocations. The core nature of both dissociated dislocations and arrays of single partial dislocations has been determined by the technique of large angle convergent beam electron diffraction. The results indicate that the core of all single partial dislocation half-loops constituting an array consists of silicon atoms. It is concluded that, with the present deformation geometry, the Si-core partial dislocations are preferentially nucleated before the C-core partial dislocations. In the case of a dissociated dislocation, when a pair of partials was present, electron microscopy observations revealed that the morphology of the two partial dislocations was very different; while the Si-core partials were smooth, the C-core partial dislocations had a zig-zag morphology.