title: Influence of the surface termination on the light emission of crystalline silicon nanoparticles.
abstract: The light emission properties of silicon crystalline nanoparticles (SiNPs) have been investigated using steady-state and time-resolved photoluminescence measurements carried out at 12 K and at room temperature. To enable a comparative study of the role of surface terminal groups on the optical properties, we investigated SiNPs-H ensembles with the same mean NP diameter but differing on the surface termination, namely organic-functionalized with 1-dodecene (SiNPs-C12) and H-terminated (SiNPs-H). We show that although the spectral dependence of the light emission is rather unaffected by surface termination, characterized by a single broad band peaking at ∼1.64 eV, both the exciton recombination lifetimes and quantum yields display a pronounced dependence on the surface termination. Exciton lifetimes and quantum yields are found to be significantly lower in SiNPs-H compared SiNPs-C12. This difference is due to distinct non-radiative recombination probabilities resulting from inter-NP exciton migration, which in SiNPs-C12 is inhibited by the energy barriers imposed by the bulky surface groups. The surface groups of organic-terminated SiPs are responsible for the inhibition of inter-NP exciton transfer, yielding a higher quantum yield compared to SiNPs-H. The surface oxidation of SiNPs-C12 leads to the appearance of a phenomenon of an exciton transference from to the Si core to oxide-related states that contribute to light emission. These excitons recombine radiatively, explaining why the emission quantum of the organic-terminated SiNPs is the same after surface oxidation of SiNPs-C12.
authors.affiliation: Department of Physics and CICECO-Aveiro Institute of Materials, University of Aveiro, 3810-193 Aveiro, Portugal. Department of Physics and I3N, University of Aveiro, Aveiro 3810-193, Portugal.
authors.forename: Alexandre M P
authors.initials: AM
authors.lastname: Botas
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Anthony
authors.forename: Jeslin
authors.initials: J
authors.lastname: Wu
authors.forename: David J
authors.initials: DJ
authors.lastname: Rowe
authors.forename: Nuno J O
authors.initials: NJ
authors.lastname: Silva
authors.forename: Uwe
authors.initials: U
authors.lastname: Kortshagen
authors.forename: Rui N
authors.initials: RN
authors.lastname: Pereira
authors.forename: Rute A S
authors.initials: RA
authors.lastname: Ferreira