O environment of unpaired Si bonds (Pb defects) at the (111)Si/SiO2 interface.

Abstract

The immediate oxygen environment in the silica side of the [111]${\mathit{P}}_{\mathit{b}}$ defect (an interfacial \ifmmode \dot{}\else \.{}\fi{}Si?${\mathrm{Si}}_{3}$ defect with an unpaired ${\mathit{sp}}^{3}$-like hybrid perpendicular to the interface) has been revealed from $^{17}\mathrm{O}$ hyperfine (HF) structure electron-spin-resonance measurements on (111)Si/${\mathrm{SiO}}_{2}$ structures enriched to 51.24% $^{17}\mathrm{O}$. The results show that the ${\mathit{sp}}^{3}$ hybrid has its strongest HF interaction, characterized by the HF splitting constant ${\mathit{a}}_{\mathrm{?}1}$=2.7\ifmmode\pm\else\textpm\fi{}0.15 G, with only one O site in a first shell, a next interaction of ${\mathit{a}}_{\mathrm{?}2}$=1.1 G with one O site in a second shell, and a third interaction of ${\mathit{a}}_{\mathrm{?}3}$\ensuremath{\approxeq}0.2 G with two equivalent O sites in a third shell. These results complete the model of the ${\mathit{P}}_{\mathit{b}}$ defect and conflict with a previously proposed tridymitelike model for the silica side of the ${\mathit{P}}_{\mathit{b}}$ defect.