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Physical Synthesis and Study of Ag@CaF 2 Core@Shell Nanoparticles: Morphology and Tuning of Optical Properties
Author(s) -
D'Addato Sergio,
Vikatakavi Avinash,
Spadaro Maria Chiara,
Valeri Sergio,
Pasquali Luca
Publication year - 2019
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201800507
Subject(s) - x ray photoelectron spectroscopy , nanoparticle , materials science , surface plasmon resonance , scanning electron microscope , wafer , layer (electronics) , nanotechnology , evaporation , analytical chemistry (journal) , chemical engineering , chemistry , physics , chromatography , engineering , composite material , thermodynamics
Pre‐formed Ag nanoparticles (NPs) and Ag@CaF 2 core–shell NPs are physically synthesized using DC magnetron‐based NP source and deposited on Si‐SiO x wafers. The samples are prepared by co‐depositing Ag nanoparticles and CaF 2 produced by an evaporation source, or by sequential deposition method, i.e., by depositing in a sequence a CaF 2 buffer layer, the Ag NPs generated by the NP source and a capping CaF 2 layer. The supported films are characterized by Scanning Electron Microscopy (SEM), X‐ray Photoelectron Spectroscopy (XPS), and Surface Differential Reflectivity (SDR). SEM shows that Ag NPs deposited directly on Si‐SiO x tend to diffuse and to agglomerate, affecting the size distribution of the nanostructures. The presence of a CaF 2 buffer layer between Ag and Si‐SiO x limits this effect, while XPS reveals electrical charging, caused by the insulating nature of the CaF 2 continuous film. The surface plasmon resonance behavior for different samples is analyzed using SDR with p‐polarized light. There is a clear evidence of a blue shift in the plasmon excitation due to the presence of CaF 2 on Si, which can represent a potential advantage for the technological applications in photovoltaics and optoelectronics.