title: A complex study of the fast blue luminescence of oxidized silicon nanocrystals: the role of the core.
abstract: Silicon nanocrystals (SiNCs) smaller than 5 nm are a material with strong visible photoluminescence (PL). However, the physical origin of the PL, which, in the case of oxide-passivated SiNCs, is typically composed of a slow-decaying red-orange band (S-band) and of a fast-decaying blue-green band (F-band), is still not fully understood. Here we present a physical interpretation of the F-band origin based on the results of an experimental study, in which we combine temperature (4-296 K), temporally (picosecond resolution) and spectrally resolved luminescence spectroscopy of free-standing oxide-passivated SiNCs. Our complex study shows that the F-band red-shifts only by 35 meV with increasing temperature, which is almost 6 times less than the red-shift of the S-band in a similar temperature range. In addition, the F-band characteristic decay time obtained from a stretched-exponential fit decreases only slightly with increasing temperature. These data strongly suggest that the F-band arises from the core-related quasi-direct radiative recombination governed by slowly thermalizing photoholes.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnická 10, 162 53, Prague 6, Czech Republic. ondic@fzu.cz.
authors.forename: Lukáš
authors.initials: L
authors.lastname: Ondič
authors.forename: Kateřina
authors.initials: K
authors.lastname: Kůsová
authors.forename: Marc
authors.initials: M
authors.lastname: Ziegler
authors.forename: Ladislav
authors.initials: L
authors.lastname: Fekete
authors.forename: Viera
authors.initials: V
authors.lastname: Gärtnerová
authors.forename: Vladimír
authors.initials: V
authors.lastname: Cháb
authors.forename: Václav
authors.initials: V
authors.lastname: Holý
authors.forename: Ondřej
authors.initials: O
authors.lastname: Cibulka
authors.forename: Kateřina
authors.initials: K
authors.lastname: Herynková
authors.forename: Mathieu
authors.initials: M
authors.lastname: Gallart
authors.forename: Pierre
authors.initials: P
authors.lastname: Gilliot
authors.forename: Bernd
authors.initials: B
authors.lastname: Hönerlage
authors.forename: Ivan
authors.initials: I
authors.lastname: Pelant