Physical Review B Condensed Matter vol:58 issue:23 pages:15801-15809
An optimized electron spin resonance study has resulted in the observation of the full angular dependence of the hyperfine interaction spectrum associated with the unpained electron of the P-b1 point defect at the thermal (100)Si/SiO2 interface, showing that the dominant interaction arises from a single Si-29 isotope. The hyperfine tensor exhibits nearly axial (weakly monoclinic I) symmetry with A(parallel to) (parallel to)=167+/-3 G and A(perpendicular to)=107 +/-4 G. Molecular-orbital analysis indicates that the unpaired electron resides for similar to 58% in a single unpaired Si hybrid orbital, found to be 14% s like and 86% p like, with the p orbital pointing closely along a  direction at 35.26 degrees with the  interface normal. If O is excluded as an immediate part of the defect, the results establish the kernel of the P-b1 defect as a tilted (similar to 22 degrees about [0(1) over bar 1]) asymmetric, likely strained, Si(3)drop Si. unit. Like P-b and P-b0, P-b1 is a prototype Si dangling bond defect. All available structural information may, in principle, be compatible with the moiety being incorporated as part of a defected strained Si-Si dimer configuration at slightly subinterfacial position. The dimer has previously been advanced as a natural building block in matching SiO2 to (100)Si. [S0163-1829(98)06440-6].