Interplay of ballistic and chemical effects in the formation of structural defects for Sn and Pb implanted silica

TL;DR

This study investigates how Sn and Pb ions interact with silica during implantation, revealing differences in clustering, bonding, and energy requirements that influence defect formation and material properties.

Contribution

It provides a comparative analysis of Sn and Pb implantation in silica, combining spectroscopy, ab initio calculations, and density functional theory to elucidate their distinct behaviors.

Findings

Pb tends to cluster in silica after implantation.

Sn forms strong bonds with oxygen in silica.

Pb requires higher energy and temperature for incorporation.

Abstract

The electronic structures of Sn and Pb implanted SiO2 are studied using soft X-ray absorption (XAS) and emission (XES) spectroscopy. We show, using reference compounds and ab initio calculations, that the presence of Pb-O and Sn-O interactions can be detected in the pre-edge region of the oxygen K-edge XAS. Via analysis of this interaction-sensitive pre-edge region, we find that Pb implantation results primarily in the clustering of Pb atoms. Conversely, with Sn implantation using identical conditions, strong Sn-O interactions are present, showing that Sn is coordinated with oxygen. The varying results between the two ion types are explained using both ballistic considerations and density functional theory calculations. We find that the substitution of Pb into Si sites in SiO2 requires much more energy than substituting Sn in these same sites, primarily due to the larger size of the Pb ions. From these calculated formation energies it is evident that Pb requires far higher temperatures than Sn to be soluble in SiO2. These results help explain the complex processes which take place upon implantation and determine the final products.