Effects of vacancy defects on the mechanical properties in neutron irradiated Czochralski silicon.

We have investigated the mechanical properties of neutron irradiated Czochralski (NICZ) silicon using nanoindentations combined with micro-Raman spectroscopy. It is found that NICZ silicon shows higher hardness (∼13% higher) than non-irradiated silicon, with a slightly lower Young's modulus. When the samples were subjected to isochronal anneals in the temperature range of 250 °C-650 °C, the hardness of NICZ silicon gradually decreases as the temperature increases and it is finally comparable to that of the non-irradiated silicon.