Activation energies for the formation and evaporation of vacancy clusters in silicon.

The thermal evolution of vacancy-type defects in Czochralski (Cz-) and epitaxially grown (epi-) silicon has been investigated using variable-energy positron annihilation spectroscopy. Heating at 300-500 degrees C caused rapid migration of divacancies and clustering of the resulting defects with activation energies of 2.1(2) and 2.7(7) eV in epi- and Cz-Si. Clustering occurred more rapidly in Cz-Si, attributed to the seeding effect of impurities. Heating at 500-640 degrees C annealed the clusters with activation energies of 3.9(3) and 3.6(3) eV in epi- and Cz-Si, linked to the vacancy-cluster binding energy.