title: Comparison of Silicon Nanocrystals Prepared by Two Fundamentally Different Methods.
abstract: This work compares structural and optical properties of silicon nanocrystals prepared by two fundamentally different methods, namely, electrochemical etching of Si wafers and low-pressure plasma synthesis, completed with a mechano-photo-chemical treatment. This treatment leads to surface passivation of the nanoparticles by methyl groups. Plasma synthesis unlike electrochemical etching allows selecting of the particle sizes. Measured sizes of the nanoparticles by dynamic light scattering show 3 and 20 nm for electrochemically etched and plasma-synthetized samples, respectively. Plasma-synthetized 20-nm particles do not exhibit photoluminescence due to absence of quantum confinement effect, and freshly appeared photoluminescence after surface passivation could indicate presence of organic molecules on the nanoparticle surface, luminescing instead of nanocrystal core. Electrochemically etched sample exhibits dramatic changes in photoluminescence during the mechano-photo-chemical treatment while no photoluminescence is observed for the plasma-synthetized one. We also used the Fourier transform infrared spectroscopy for comparison of the chemical changes happened during the treatment.
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00, Prague, Czech Republic. cibulka@fzu.cz.
authors.forename: Ondřej
authors.identifier: http://orcid.org/0000-0002-7812-7277
authors.initials: O
authors.lastname: Cibulka
authors.affiliation: Institute for Experimental Physics II: Coupled Plasma-Solid State Systems, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Vorkötter
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00, Prague, Czech Republic.
authors.forename: Adam
authors.initials: A
authors.lastname: Purkrt
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00, Prague, Czech Republic.|CTU Faculty of Electrical Engineering, Technická 2, 166 27, Prague, Czech Republic.
authors.forename: Jakub
authors.initials: J
authors.lastname: Holovský
authors.affiliation: Institute for Experimental Physics II: Coupled Plasma-Solid State Systems, Ruhr-University Bochum, 44780, Bochum, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Benedikt
authors.affiliation: Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 00, Prague, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Herynková
keywords: Electrochemical etching; Low-pressure plasma; Photoluminescence; Silicon nanocrystals; Size distribution; Surface passivation