The {100} and {110} faces of n-type GaSb, and the (110) face of n-type GaAs, were indented at room temperature and 200C. The plastic zone around the micro-indentations was then investigated by means of transmission electron microscopy. In both materials, indentation rosettes with approximately 2-fold symmetry formed around the indentations. In general, the rosettes consisted of dislocations and micro-twins. The rosette arms in n-type (001) GaSb were only slightly asymmetrical along the two <110> directions; with the longer arms corresponding to -type dislocations. This implied that the mobility of -dislocations in GaSb was higher than that of  dislocations. In both materials, the 90 perfect and partial dislocations had the highest mobility. On the basis of these results, it was proposed that perfect dislocations in these materials nucleated on the indentation facets as half-loops; with Burgers vectors that were parallel to the propagation directions of the rosette arms. On the other hand, twinning dislocations nucleated on the indentation surface as partial dislocation half-loops. A mechanism for indentation twinning was proposed in which the step that was created by surface nucleation of a dislocation half-loop acted as a preferential site for the nucleation of the next half-loop on an adjacent {111} plane.

X.J.Ning, T.Perez, P.Pirouz: Philosophical Magazine A, 1995, 72[4], 837-59