Chemical nature of active sites for defect‐mediated nucleation on silicon dioxide

Germanium nanoparticle growth on SiO 2 proceeds via defect‐mediated nucleation and particle density can be enhanced by chemically treating the SiO 2 with SiH x . The influence of SiH x fragments on SiO 2 surface sites is studied using a fluorescent probe‐based technique to understand the chemical nature of the inherent defect trapping sites and the chemical nature of the additional trapping sites formed by SiH x . Oxygen‐vacancy sites on SiO 2 are the inherent sites for defect‐mediated nucleation. SiH x fragments, generated by cracking disilane on a hot tungsten filament, are shown to react with strained siloxane sites, leading to a conversion of these strained siloxane sites into a different low density defect site that is shown to display reactive characteristics similar to the oxygen‐vacancy defect sites. Previous work demonstrating an increased density of Ge nuclei on SiO 2 surfaces with increasing SiH x exposure is interpreted in the context of the current experimental results. © 2015 American Institute of Chemical Engineers AIChE J , 62: 367–372, 2016