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

Abstract

A variety of electron-spin-resonance (ESR) spectra of dangling bond $(g=2.0055)$ in undoped hydrogenated amorphous silicon $(a\ensuremath{-}\mathrm{S}\mathrm{i}:\mathrm{H})$ 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 $(\ensuremath{\nu}=3\char21{}34\mathrm{GHz})$ and ${}^{29}\mathrm{Si}$ 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 ${}^{29}\mathrm{Si}$ hf structure), and also have simulated \ensuremath{\nu} 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 ${}^{29}\mathrm{Si}$ hyperfine interactions were determined to be approximately 7.4 and 2.1 mT, respectively, and ${g}_{\ensuremath{\parallel}}=2.0039,$ ${g}_{\ensuremath{\perp}}=2.0065.$ 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 ${\mathrm{SiO}}_{2},$ the ${P}_{b}$ center.