Fundamental chemical differences among P_b defects on (111) and (100) silicon

Using electron spin resonance, a single defect (called Pb0) is observed at the Si(111)/SiO2 interface, whereas two different defects (called Pb0 and Pb1) are observed at the Si(100)/SiO 2 interface. While the structure of the Pb center is well established as a silicon dangling bond, the identities of Pb0 and Pb1 are controversial. We have discovered that under processing conditions where the hydrogen passivation reaction Si·+H 0→Si-H passivates the Pb center at the Si(111)/SiO2 interface, the Pb1 center is likewise passivated but the Pb0 center is not. We conclude that the structure of Pb1 is a silicon dangling bond similar to the Pb on (111), and that the Pb0 is a fundamentally different defect, in agreement with recent theoretical calculations.