EPR of a〈001〉Si interstitial complex in irradiated silicon

Abstract

This paper deals with an electron-paramagnetic-resonance study of the $\mathrm{Si}\ensuremath{-}B3$ center, which was first reported by Daly. The $\mathrm{Si}\ensuremath{-}B3$ center is a secondary defect which forms upon annealing between 50 and 175\ifmmode^\circ\else\textdegree\fi{}C in irradiated boron-doped silicon and is stable up to $\ensuremath{\approx}500$\ifmmode^\circ\else\textdegree\fi{}C. Our studies indicate that the $\mathrm{Si}\ensuremath{-}B3$ center exhibits only a high-temperature stress response which is indicative of a thermally activated atomic reorientation at $T\ensuremath{\gtrsim}400$\ifmmode^\circ\else\textdegree\fi{}C. This defect does not exhibit a low-temperature stress response indicative of Jahn-Teller effects; consequently, the $\mathrm{Si}\ensuremath{-}B3$ center has inherent ${D}_{2d}$ symmetry by virtue of its molecular structure. The kinetics of this defect, the nature of the $^{29}\mathrm{Si}$ hyperfine interactions, and the symmetry of the defect suggest that the $\mathrm{Si}\ensuremath{-}B3$ corresponds to either a $〈001〉$ Si di-interstitial or a $〈001〉$ Si split interstitial. The $\mathrm{Si}\ensuremath{-}B3$ center appears to be similar but not identical to the $\mathrm{Si}P6$ center, which Lee and Corbett have recently suggested corresponds to a $〈001〉$ Si di-interstitial.