In situ electron microscopy of the phases of Cu₃Si

Abstract

The transformations between the η and η′ phases of Cu₃Si were studied by in situ transmission electron microscope (TEM) diffraction analysis and by differential scanning calorimetry (DSC). The space groups of η and η′ are and , respectively. The lattice parameters of η are a = 4.06 Å and c = 7.33 Å. The η′ phase results from faulted stacking of the η unit cell, and has lattice parameters: a = 35.16 Å and c = 21.99 Å. A long-period anti-phase domain structure appears in these two phases and is part of a sequence of phase transformations from η′ to η upon heating. The Cu silicide precipitates that form in voids in silicon are the η′ phase, oriented in the silicon matrix according to: (0001)_η'∥(110)_Si; [001]_Si.

Acknowledgements

This work was supported by the National Science Foundation as a Cooperative Activity in Materials Science between NSF and the European Commission. We thank Xi Wang for his help with thin film deposition.