Annealing of nanoindentation-induced high pressure crystalline phases created in crystalline and amorphous silicon

Thermally induced phase transformation of Si-III/Si-XII zones formed by nanoindentation has been studied during low temperature 200 T 300 °C thermal annealing by Raman microspectroscopy and transmission electron microscopy. Two sizes of spherical indenter tips have been used to create substantially different volumes of phase transformed zones in both crystalline c-Si and amorphous silicon a-Si to study the zone size and starting matrix effects. The overall transformation is from Si-III/XII to polyor nanocrystalline Si-I through intermediate phases of Si-XIII and Si-IV. Attempts have been made to determine the exact transformation pathways. Two scenarios are possible: either Si-XII first transforms to Si-III before transforming to Si-I through the intermediate phases or that Si-XII goes through the intermediate phases while Si-III transforms directly to Si-I. Finally, the phase transformations are slower in the larger indents and the starting matrix crystalline or amorphous has a substantial effect on the transformation kinetics of the small indents compared to the larger ones. We attribute this increased stability to both matrix effects nucleation and a difference in overall residual stress in indents made in a-Si compared to c-Si. © 2009 American Institute of Physics. DOI: 10.1063/1.3124366