High-temperature nitrogen annealing induced bonding states and photoluminescence changes in inductively coupled plasma torch synthesized silicon nanostructures

In this work, we investigate the optical properties of self-standing Si nanostructures (SiNS) as-grown, by an inductively coupled plasma torch process, and after their annealing under N2 flux at 1200 °C. We show that as-grown SiNS are embedded in a silicon oxide shell while part of the annealed SiNS transforms into silicon nitrides or oxynitrides. The analysis of the photoluminescence spectra and maps of both as-grown and annealed SiNS enabled us to confirm the occurrence of quantum confinement effects in the ultra-small SiNS and to highlight the role played by the silicon oxide, silicon nitrides, and silicon oxynitrides nanophases in the photoluminescence emission.