Microscopic Structure of Er-Related Optically Active Centers in Crystalline Silicon

A successful observation and analysis of the Zeeman effect on the λ≈1.54 μm photoluminescence band in Er-doped crystalline MBE-grown silicon are presented. The symmetry of the dominant optically active centers is conclusively established as orthorhombic I(C₂ᵥ) with g_∥≈18.39 and g_⊥≈0. In this way the long standing puzzle as regards the paramagnetism of optically active Er-related centers in silicon is settled. Preferential generation of a single type of an optically active Er-related center confirmed in this study is essential for photonic applications of Si:Er.