LACBED study of extended defects in 4H-SiC

Large-angle convergent-beam electron diffraction analysis was successfully performed on pairs of partial dislocations so close that their effect on Bragg lines overlap. These pairs, dragging 3C layers, were nucleated by mechanical deformation of 4H-SiC. Splitting of Bragg lines on crossing a dislocation pair can be interpreted as resulting from a single dislocation having a Burgers vector (B) over right arrow equal to the sum of the two partial dislocation ones. Splitting rules using phase-shifted reflections ((g) over right arrow g . (b) over right arrow not equal n, with n is an element of Z) are also given depending on the phase shift produced by 3C lamellae. These results give a (b) over right arrow b direction in agreement with weak-beam dark-field studies and suggest that Si core dislocations have highest mobilities for low-temperature (<700 degrees C) plastic deformation.