Observation of the localized Si dangling-bond $P_b$ defect at the Si/${\mathrm{Si}}_3$${\mathrm{N}}_4$ interface

Low-temperature electron-spin resonance (ESR) reveals the presence of the $P_b$ defect (identified with Si≡${\mathrm{Si}}_3$) at the thermally grown (111)Si/${\mathrm{Si}}_3$ ${\mathrm{N}}_4$ interface. This constitutes the first observation of this defect (called $P_{\mathrm{bN}}$) at a natural Si/solid interface other than the Si/Si${\mathrm{O}}_2$ one. It is argued that ESR analysis of the $P_{\mathrm{bN}}$ center is a powerful tool for characterizing the Si/${\mathrm{Si}}_3$ ${\mathrm{N}}_4$ interface on an atomic scale. This observation again confirms $P_b$ as a prototype dangling-bond center, its main properties being determined by the backside Si matrix.