Similar point defects in crystalline and amorphous silicon

The microscopic nature of defects in ion-implanted crystalline silicon (c-Si) and amorphous silicon (a-Si) has been studied using Mössbauer spectroscopy. The evolution of the local structure around the probe atoms is followed during thermal annealing of ion-beam-created amorphous and ion-beam-damaged crystalline Si. Direct comparison of the Mössbauer parameters of ¹¹⁹Sb in c-Si and a-Si demonstrates that Sb occupies two distinct sites in each material with similar local environments in both materials. These sites are identified as fourfold-coordinated substitutional Sb and Sb-vacancy complexes. Annealing of ion-beam-damaged c-Si at 150³ C causes the Sb-vacancy complex to change from a substitutional Sb adjacent to a vacancy to a more complicated complex. Annealing of a-Si is shown to reduce distortions in the network, consistent with structural relaxation.