Size-dependent critical transition in the origin of light emission from core-shell Si-SiO2nanoparticles

Bruno P. Falcão, Joaquim P. Leitão, Maria R. Soares, J. Rodrigues, Lídia Ricardo, Hugo Águas, Rodrigo Martins, Rui N. Pereira

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)

Abstract

The origin of the light emission from nanosilicon systems, such as crystalline silicon nanoparticles (Si-NPs), has been an intensively debated issue, with seemingly contradicting literature results pointing to different mechanisms. Here, the origin of the photoluminescence (PL) from application-grade Si-SiO2 core-shell nanoparticles with different sizes and synthesized with the industrially scalable high-yield nonthermal silane plasma method has been elucidated. It is found that the commonly observed PL from these Si-NPs originates, in general, from two processes: recombination within the nanoparticle silicon core and recombination within the oxide shell. The photon energies of both emissions increase with decreasing nanoparticle size. Importantly, a nanoparticle size dependence of the relative contribution of the two processes to the overall PL is established. For large (small) Si-NPs, the luminescence is dominated by the core (oxide-shell) emission. Interestingly, the transition between these two regime limits occurs within an extremely narrow nanoparticle size range (∼0.5 nm). This critical transition, in combination with the close photon energies of the two emission components, is responsible for the common observation of only a single unstructured PL band for Si-NPs and for the seemingly conflicting assignments of the origin of this luminescence found in the literature for apparently similar Si-NPs. This journal is

Original languageEnglish
Pages (from-to)9012-9023
Number of pages12
JournalJournal of Materials Chemistry C
Volume8
Issue number26
DOIs
Publication statusPublished - 14 Jul 2020

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