Delocalized Nature of the E'-delta Center in Amorphous Silicon Dioxide

TL;DR

This study uses Electron Paramagnetic Resonance to analyze the E'-delta defect in amorphous silicon dioxide, revealing that its unpaired electron wave function is delocalized over four silicon atoms, which advances understanding of defect structures.

Contribution

The paper provides the first experimental evidence that the E'-delta center's unpaired electron is delocalized over multiple silicon atoms in amorphous SiO2.

Findings

The hyperfine doublet intensity indicates delocalization over four silicon atoms.

The E'-delta center's electron wave function is not localized but spread across multiple atoms.

Gamma ray irradiation induces the E'-delta defect in amorphous silicon dioxide.

Abstract

We report an experimetal study by Electron Paramagnetic Resonance (EPR) of E'-delta point defect induced by gamma ray irradiation in amorphous SiO2. We obtained an estimetion of the intensity of the 10 mT doublet characterizing the EPR spectrum of such a defect arising from hyperfine interaction of the unpaired electron with a 29Si (I=1/2) nucleus. Moreover, determining the intensity ratio between this hyperfine doublet and the main resonance line of E'-delta center, we pointed out that unpaired electron wave function of this center is actually delocalized over four nearly equivalent silicon atoms.