Deformation of silicon at low temperatures

The dislocation arrangements produced around microhardness indentations made in silicon at room temperature have been studied by transmission electron microscopy. Loops consisting of 30°- and 60°-dislocations are produced and move on the {111} planes. It is suggested that, during indentation, the theoretical shear strength is exceeded locally and that the observed dislocations arise as a result of the accommodation of the displacements due to block slip. On annealing up to 1030° C the loops do not appear to be mobile, rather new loops consisting of edge and screw components are formed which can move large distances.