The production of excess interstitials by pre-amorphisation

Single-crystal silicon has been amorphised by bombardment with Si + , Ge + or Sn + ions. After conventional annealing (900 degrees C, 30 min) some disorder remained. The amount was measured by ion channelling and transmission electron microscopy and compared with the quantity of excess interstitials predicted by the Monte Carlo computer program TRIM. Both the predicted and measured integral disorder fell as the atomic weight of the projectile increased. Because lattice strain also leads to a reduction in ion channelling this had to be taken into account when estimating residual damage from back-scattering analysis. The results indicate that there are six scattering centres per interstitial.