Cold nanoindentation of germanium

Diamond cubic Ge is subjected to high pressures via nanoindentation at temperatures between −45 °C and 20 °C. The residual impressions are studied using ex-situ Raman microspectroscopy and cross-sectional transmission electron microscopy. The deformation mechanism at 20 °C is predominately via the generation of crystalline defects. However, when the temperature is lowered, the analysis of residual indentation impressions provides evidence for deformation by phase transformation and formation of additional phases such as r8-Ge, hd-Ge, and amorphous Ge. Furthermore, these results show that at 0 °C and below, dc-Ge will reliably phase transform via nanoindentation.