Effect of temperature on metastable phases induced in silicon during nanoindentation

Indentations were performed on silicon using a Berkovich indenter at loads up to 12 mN, at temperatures from 20 to 135 degrees C. Transmission electron microscopy revealed crystalline silicon phases in the residual indentation imprint at and above 35 degrees C. Also, the first reconfirmation of the occurrence of Si-VIII during unloading was observed at temperatures of 100 and 125 degrees C. Interestingly, at 125 degrees C a cavity was also observed, and an unidentifiable phase was observed at 135 degrees C. The observations show the strong effect of temperature on pressure-induced phase transformation in silicon.