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Work function and negative electron affinity of ultrathin barium fluoride films
Author(s) -
Mezzi Alessio,
Bolli Eleonora,
Kaciulis Saulius,
Mastellone Matteo,
Girolami Marco,
Serpente Valerio,
Bellucci Alessandro,
Carducci Riccardo,
Polini Riccardo,
Trucchi Daniele M.
Publication year - 2020
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6832
Subject(s) - work function , x ray photoelectron spectroscopy , ultraviolet photoelectron spectroscopy , thin film , materials science , analytical chemistry (journal) , barium fluoride , electron affinity (data page) , thermionic emission , substrate (aquarium) , barium , photoemission spectroscopy , vacuum evaporation , electron , chemistry , nanotechnology , chemical engineering , physics , oceanography , organic chemistry , layer (electronics) , chromatography , quantum mechanics , molecule , geology , nuclear physics , engineering , metallurgy
Thin films of barium fluorides with different thicknesses were deposited on GaAs substrate by electron beam evaporation. The aim of the work was to identify the best growth conditions for the production of coatings with a low work function suitable for the anode of hybrid thermionic‐photovoltaic (TIPV) devices. The chemical composition and work function φ of the films with different thicknesses were investigated by X‐ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS). The lowest value of φ = 2.1 eV was obtained for the film with a thickness of ~2 nm. In the valence band spectra of the films at low kinetic energy, near the cutoff, a characteristic peak of negative electron affinity was present. This effect contributed to a further reduction of the film's work function.