Atomic structure of theB3defect in neutron-irradiated silicon

Abstract

The tetragonal ${(D}_{2d}$ symmetry) $\mathrm{Si}\ensuremath{-}B3$ defect is intensively observed by electron spin resonance (ESR) in neutron-irradiated Cz-grown c-Si after annealing in the range $250--500\ifmmode^\circ\else\textdegree\fi{}\mathrm{C}.$ In addition to the limited known one, a rich ${}^{29}\mathrm{Si}$ hyperfine structure is revealed and fully angularly mapped. Spectra simulations show that the defect unpaired electron has its strongest hf interaction with two equivalent Si sites in the first shell, a next interaction with four equivalent Si sites in the second shell, and a last interaction with eight equivalent Si sites in the third shell. From comparison of the data with extensive theoretical calculations on the tetrainterstitial ${(I}_{4}),$ the $\mathrm{Si}\ensuremath{-}B3$ is identified as the ${I}_{4}$ defect.