2 9Si hyperfine structure of unpaired spins at the Si/SiO2 interface

The hyperfine spectrum associated with unpaired electrons at the (111) Si/SiO2 interface (Pb centers) is reported for the first time. Electron paramagnetic resonance measurements indicate that the hyperfine interaction S↘⋅Ā⋅I↘ arises from the 29Si isotope and is characterized by A∥=146.(±5.)×10−4 cm−1 and A⊥=85.(±8.)×10−4 cm−1. An analysis of this hyperfine interaction firmly establishes many of the details in the structure of this interface defect.