Electronic structure and photoluminescence properties of Zn-ion implanted silica glass before and after thermal annealing

TL;DR

This study investigates how Zn-ion implantation and thermal annealing alter the electronic structure and photoluminescence of silica glass, revealing formation of ZnO-like nanoparticles and phase changes that enhance green emission.

Contribution

It combines experimental XPS and photoluminescence data with DFT calculations to elucidate defect formation and phase evolution in Zn-implanted silica glass.

Findings

Zn-ions prefer interstitial sites over substitutional ones.

Thermal annealing reduces ZnO nanoparticles and promotes -Zn2SiO4 formation.

Green photoluminescence is significantly enhanced after annealing.

Abstract

The results of XPS core-level and valence band measurements, photoluminescence spectra of a-SiO2 implanted by Zn-ions (E=30 keV, D=1*1017 cm^-2) and Density Functional Theory calculations of electronic structure as well as formation energies of structural defects in silica glass induced by Zn-ion implantation are presented. Both theory and experiment show that it is energetically more favorable for implanted zinc ions to occupy the interstitial positions instead of cation substitution. As a result, the Zn-ions embedded to interstitials, form chemical bonds with the surrounding oxygen atoms, formation ZnO-like nanoparticles and oxygen-deficient SiOx matrix. The subsequent thermal annealing at 900 0C (1 hr) strongly reduces the amount of ZnO nanoparticles and induces the formation of {\alpha}-Zn2SiO4 phase which markedly enhances the green emission.