Excitons in Silicon Nanocrystalites: The Nature of Luminescence

TL;DR

This study investigates the excitonic luminescence properties of silicon nanocrystals up to 1 nm in size using first-principles calculations, revealing the impact of surface bonding on their optical features.

Contribution

It provides new insights into how Si-O-Si bridge bonds influence luminescence in silicon nanocrystals, supported by detailed first-principles simulations.

Findings

Si-O-Si bridge bonds induce visible-range luminescence

Calculated spectra agree with experimental data

Surface chemistry significantly affects excitonic properties

Abstract

The absorption and emission spectra of silicon nanocrystals up to 1 nm diameter including geometry optimization and the many-body effects induced by the creation of an electron-hole pair have been calculated within a first-principles framework. Starting from hydrogenated silicon clusters of different size, different Si/O bonding at the cluster surface have been considered. We found that the presence of a Si-O-Si bridge bond originates significative excitonic luminescence features in the visible range that are in fair agreement with the experimental outcomes.