Dangling Bond Defects atSi−SiO2Interfaces: Atomic Structure of thePb1Center

Abstract

Using a first-principles approach, we characterize dangling bond defects at $\mathrm{Si}-{\mathrm{SiO}}_2$ interfaces by calculating hyperfine parameters for several relaxed structures. Interface models, in which defect Si atoms remain close to crystalline sites of the substrate upon relaxation, successfully describe $P_b$ and $P_{b0\mathrm{}}$ defects at (111) and (100) interfaces, respectively. On the basis of calculated hyperfine parameters, we discard models of the $P_{b1\mathrm{}}$ defect containing a first neighbor shell with an O atom or a strained bond. A novel model consisting of an asymmetrically oxidized dimer yields hyperfine parameters in excellent agreement with experiment and is proposed as the structure of the $P_{b1\mathrm{}}$ center.