title: Origin of visible photoluminescence from arrays of vertically arranged Si-nanopillars decorated with Si-nanocrystals.
abstract: Arrays of vertically aligned Si-nanopillars, with average diameters of 100 nm and 5 μm length, have been prepared by wet chemical etching of crystalline silicon in a special manner. Samples with smooth- and porous-walled nanopillars have been studied. In the case of the latter, Si-nanocrystals, passivated with SiO(x), decorating the surface of the nanopillars are identified by the means of TEM and FTIR. When excited by UV-blue light, the porous-walled Si-nanopillars are found to have a strong broad visible emission band around 1.8 eV with a nearly perfect Gaussian shape, μs luminescence lifetimes, minor emission polarization and a non-monotonic temperature dependence of luminescence. The Si-nanocrystal surface is found to be responsible for the luminescence. The red-shift of the emission maximum and the luminescence quenching induced by oxidation in UV-ozone confirm this assumption. A model of luminescence involving UV photon absorption by Si-nanocrystals with subsequent exciton radiative recombination on defect sites in SiO(x) covering Si-nanocrystals has been proposed. Possible applications of the nanopillar arrays are discussed.
authors.affiliation: INPAC-Institute for Nanoscale Physics and Chemistry, KU Leuven, Belgium. Aleksandr.Kuznetsov@fys.kuleuven.be
authors.forename: A S
authors.initials: AS
authors.lastname: Kuznetsov
authors.forename: T
authors.initials: T
authors.lastname: Shimizu
authors.forename: S N
authors.initials: SN
authors.lastname: Kuznetsov
authors.forename: A V
authors.initials: AV
authors.lastname: Klekachev
authors.forename: S
authors.initials: S
authors.lastname: Shingubara
authors.forename: J
authors.initials: J
authors.lastname: Vanacken
authors.forename: V V
authors.initials: VV
authors.lastname: Moshchalkov