Oxygen-Oxygen defects

  Although oxygen is able to complex with a wide variety of other point defects such as vacancies, carbon and nitrogen atoms, probably the most important reactions of O in Cz-Si are those involving aggregation of more than one O_i atom. Oxygen aggregates are believed to be responsible for the family of thermal donors (with the possible addition of Si_i), and it has been speculated that fast diffusing pairs of oxygen atoms may dominate many of the defect formation processes.

In this chapter, we examine the way oxygen behaves in silicon without any other point defects present. We initially examine isolated O_i, and then an oxygen dimer, O_2i. This includes structural and vibrational mode analysis, as well as determination of the migration barrier and path. We then go on to look briefly at higher order oxygen complexes such as the trimer, O_3i, and discuss their implications in the development of other defect species such as thermal donors. Since this is still very much work in progress, many of the conclusions are necessarily open ended.