Structure of multiple-vacancy (oxygen) centers in irradiated silicon

Analysis of a new paramagnetic spin 1 spectrum, labeled Si-S1, indicates that it corresponds to the neutral charge state of the Si-B1 center in an excited spin-triplet state. An extension of this analysis to the Si-P1, -P2, -P3, -P4, and -P5 centers suggest that these centers comprise a family of defects which consist of a string of neighboring vacancies in a single (110) plane. In particular, it appears that the Si-P1 center is an odd ( 3)-vacancy defect; the Si-P2 center is a 2-vacancy, oxygen defect; the Si-P3 center is a 4-vacancy defect; the Si-P4 center is a 3-vacancy, oxygen defect of symmetry lower than C_2v ; and the Si-P5 center is a 3-vacancy, oxygen defect having C_2v symmetry.