Aggregate defects of gold and platinum with lithium in silicon: I. Magnetic resonance investigations

Trigonal and orthorhombic Au (Pt) defects in Si additionally doped with Li and P, previously investigated with electron paramagnetic resonance (EPR), are shown to be aggregate defects involving substitutional Au (Pt) and interstitial Li. The small Li hyperfine interactions, not resolved in EPR, could be measured with electron nuclear double resonance (ENDOR). With double ENDOR it is established that the trigonal defects consist of AuSi-Li₃ (PtSi-Li₃) aggregates, while the orthorhombic defects are AuSi-Li (PtSi-Li) pair defects. For the trigonal defects the Li hyperfine interaction matrices are asymmetric. The smallness of the Li hyperfine interaction suggests ionic bonding between the interstitial Li ions and the substitutional AuSi (PtSi) atoms.