Temperature-dependent mechanical deformation of silicon at the nanoscale: Phase transformation versus defect propagation

This study uses high-temperature nanoindentation coupled with in situ electrical measurements to investigate the temperature dependence (25-200 degrees C) of the phase transformation behavior of diamond cubic (dc) silicon at the nanoscale. Along with in situ indentation and electrical data, ex situ characterizations, such as Raman and cross-sectional transmission electron microscopy, have been used to reveal the indentation-induced deformation mechanisms. We find that phase transformation and defect propagation within the crystal lattice are not mutually exclusive deformation processes at elevated temperature. Both can occur at temperatures up to 150 degrees C but to different extents, depending on the temperature and loading conditions. For nanoindentation, we observe that phase transformation is dominant below 100 degrees C but that deformation by twinning along {111} planes dominates at 150 degrees C and 200 degrees C. This work, therefore, provides clear insight into the temperature dependent deformation mechanisms in dc-Si at the nanoscale and helps to clarify previous inconsistencies in the literature. (c) 2015 AIP Publishing LLC.