Electron-spin-resonance center of dangling bonds in undopeda−Si:H

A variety of electron-spin-resonance (ESR) spectra of dangling bond (g=2.0055) in undoped hydrogenated amorphous silicon (a-Si:H) have been measured by the echo-detected ESR of pulsed ESR as well as the usual continuous-wave (cw) ESR for a wide range of two experimental parameters of microwave frequency (ν=3–34 GHz) and 29Si content (p=1.6, 4.7, 9.1 at. %). Using those spectra, we have carried out spectral simulations on the whole dangling bond spectrum (a primary line and 29Si hf structure), and also have simulated ν and p dependence of the spectra. From detailed simulation analyses, we confirmed a previous identification of the dangling bond center by Stutzmann and Biegelsen [Phys. Rev. B 40, 9834 (1989)], and raised the reliability of ESR parameters; isotropic and anisotropic 29Si hyperfine interactions were determined to be approximately 7.4 and 2.1 mT, respectively, and g∥=2.0039, g⊥=2.0065. The ESR parameters indicate that the dangling bond center is localized predominantly on a single Si atom and is characterized as strongly p like, which are consistent with the case of the dangling bond at the interface between crystalline Si and SiO2, the Pb center