Non-Planar Slip and Cross-Slip at the Onset of Plastic Deformation in Silicon

The first stages of plastic deformation of FZ silicon single crystals were investigated by in situ synchrotron radiation topography, in creep conditions at temperatures between 975 and 1075 K and applied stresses from 22 to 44 MPa. Silicon samples were initially dislocation-free and deformation started at Vickers indentations and surface damage. Several features relevant for dislocation multiplication were observed: cross-slip in the bulk as well as near the surface, development of prismatic half-loops, non-planar development of dislocations in slip bands, in the wake of leading segments.