Mechanical deformation, by spherical indentation, of crystalline samples was studied by means of cross-sectional transmission electron microscopy and atomic force microscopy. All of the loading-unloading curves exhibited a discontinuity (so-called pop in) during loading. Slip bands which were oriented along {111} planes were visible in the cross-sectional transmission electron micrographs of residual indentations, and no sign of any phase transformation was found. Higher-load indentations (50mN) also led to sub-surface cracking. The sub-surface cracks were thought to be nucleated by high stress concentrations which were caused by dislocation pile-ups.

Mechanical Deformation of InP and GaAs by Spherical Indentation. J.E.Bradby, J.S.Williams, J.Wong-Leung, M.V.Swain, P.Munroe: Applied Physics Letters, 2001, 78[21], 3235-7