The details of indentation-induced mechanical deformation were studied. In particular, the origin of discontinuities in load-penetration curves during loading (pop-in events) was examined. Cross-sectional transmission electron microscopic samples of indentations were prepared by using focussed ion-beam milling. Atomic force microscopy was used to examine the surface deformation following indentation. Slip appeared to be the prime mechanism of plastic deformation, and, in contrast to Si, no evidence of pressure-induced phase changes was found. Slip along the {111} planes was clearly observed by means of cross-sectional transmission electron microscopy and atomic force microscopy, following indentation above the pop-in threshold. At high loads, sub-surface median cracking was also revealed. This cracking appeared to be nucleated at the intersection of the slip planes, and suggested that dislocation pile-ups at the slip-band intersection - and the resultant shear stress build-up - caused nucleation of a micro-crack.

Spherical Indentation of Compound Semiconductors. J.E.Bradby, J.S.Williams, J.Wong-Leung, S.O.Kucheyev, M.V.Swain, P.Munroe: Philosophical Magazine A, 2002, 82[10], 1931-9