Dislocation shielding at elevated temperatures in pre-cracked microscale silicon

Increasing evidence demonstrates that some ceramics and semiconductors can possess increased ductility and fracture toughness at lower temperatures than previously thought. The present study focuses on the unlikely candidate of single-crystal silicon, which is studied using microscale bending beams at elevated temperature. A potential solution for the issue of focused ion beam (FIB) pre-notches is also presented, by re-propagating arrested cracks. This allows for proper measurement of stress intensity from nearly atomically sharp cracks, along with removing any potential influence of Gallium. This does not mean the crack is initially dislocation free but does represent an appropriate microstructure that might be experienced in a manufacturing setting. Through post mortem transmission electron microscopy (TEM) of thinned samples after testing between 300 and 873 K, dislocation nucleation is observed at temperatures near 500 K. Beyond 500 K, there is increased propensity toward dislocation enhanced toughening through either crack-tip shielding and/or generalized plasticity.