O environment of unpaired Si bonds (Pbdefects) at the (111)Si/SiO2interface

Abstract

The immediate oxygen environment in the silica side of the [111]${\mathit{P}}_{\mathit{b}}$ defect (an interfacial ̇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±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 ${\mathit{a}}_{\mathrm{?}3}$≊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.