Dimer interaction with other defects

  Rapidly diffusing dimer pairs allows us to explain many of the apparently anomalous defect formation behaviour of other complexes in silicon. These have been discussed in the relevant chapters but are summarised briefly here:

1.

There are several different formation process for VO₂, and one of these does not result in any loss of [O_i]; indeed, O_i is produced when $\rm VO \rightarrow VO_2$ by this unknown process. It seems likely this is the breakup of VO followed by trapping of V by a dimer (Chapter 5).

2.

The anomalous formation of thermal donors has been discussed briefly here, and in more depth in Chapter 9. It seems that thermal donors are formed through the aggregation of rapidly diffusing dimers.

3.

In the early stages of annealing C-rich Cz-Si there is strong C_s and C_sO_i signals; after anneals at 450$^\circ$C these are replaced with a weaker C_sO₂ signal and stronger C_sO₃ signal [239]. These can form through dimer aggregation to the earlier C_s and C_sO_i defects, and this is discussed further in Chapter 10.

The work performed on NNO defects involved anneals in temperature ranges at which the dimer is no longer stable.