Photochemical generation of E' centre from Si-H in amorphous SiO2 under pulsed ultraviolet laser radiation

TL;DR

This study investigates how pulsed ultraviolet laser radiation induces E' centers in amorphous SiO2 by breaking Si-H bonds, revealing a two-photon process and defect-annealing dynamics.

Contribution

It introduces a kinetic model for defect generation and annealing in SiO2 under UV laser irradiation, supported by experimental optical absorption data.

Findings

Defect generation follows a two-photon mechanism.

Defect growth saturates due to annealing with mobile hydrogen.

A rate equation effectively models defect kinetics.

Abstract

In situ optical absorption spectroscopy was used to study the generation of E' centres in amorphous SiO_2 occurring by photo-induced breaking of Si-H groups under 4.7eV pulsed laser radiation. The dependence from laser intensity of the defect generation rate is consistent with a two-photon mechanism for Si-H rupture, while the growth and the saturation of the defects are conditioned by their concurrent annealing due to reaction with mobile hydrogen arising from the same precursor. A rate equation is proposed to model the kinetics of the defects and tested on experimental data.