Understanding pressure-induced phase-transformation behavior in silicon through in situ electrical probing under cyclic loading conditions

Cyclic indentation of crystalline silicon exhibits interesting pressure-induced phase-transformation behavior whereby sequential changes in the phase composition ultimately lead to a catastrophic ("pop-out") event during subsequent cycles and complete transformation to high pressure Si-III and Si-XII phases. This study combines in situ electrical measurements with cyclic loading to monitor such phase-transformation behavior. We find that, if a pop-out is not observed on the unloading curve, the end phase is predominantly amorphous but a small and increasing volume of Si-III/Si-XII results with each cycle. At a critical Si-III/Si-XII volume, pop-out can occur on a subsequent cycle, whereafter Si-III/Si-XII dominates the indent volume.