A1 Refereed original research article in a scientific journal
Topography and work function measurements of thin MgO(001) films on Ag(001) by nc-AFM and KPFM
Authors: Bieletzki M, Hynninen T, Soini TM, Pivetta M, Henry CR, Foster AS, Esch F, Barth C, Heiz U
Publisher: ROYAL SOC CHEMISTRY
Publication year: 2010
Journal: Physical Chemistry Chemical Physics
Journal name in source: PHYSICAL CHEMISTRY CHEMICAL PHYSICS
Journal acronym: PHYS CHEM CHEM PHYS
Volume: 12
Issue: 13
First page : 3203
Last page: 3209
Number of pages: 7
ISSN: 1463-9076
DOI: https://doi.org/10.1039/b923296f
Abstract
The surface topography and local surface work function of ultrathin MgO(001) films on Ag(001) have been studied by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). First principles calculations have been used to explain the contrast formation of nc-AFM images. In agreement with literature, thin MgO films grow in islands with a quasi rectangular shape. Contrary to alkali halide films supported on metal surfaces, where the island heights can be correctly measured, small MgO islands are either imaged as depressions or elevations depending on the electrostatic potential of the tip apex. Correct island heights therefore cannot be given without knowing the precise contrast formation discussed in this paper. KPFM shows a silver work function which is reduced by the MgO islands. The values for the work function differences for one and two layer thin films are -1.1 and -1.4 eV, respectively, in good agreement with recent calculations and experiments.
The surface topography and local surface work function of ultrathin MgO(001) films on Ag(001) have been studied by noncontact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM). First principles calculations have been used to explain the contrast formation of nc-AFM images. In agreement with literature, thin MgO films grow in islands with a quasi rectangular shape. Contrary to alkali halide films supported on metal surfaces, where the island heights can be correctly measured, small MgO islands are either imaged as depressions or elevations depending on the electrostatic potential of the tip apex. Correct island heights therefore cannot be given without knowing the precise contrast formation discussed in this paper. KPFM shows a silver work function which is reduced by the MgO islands. The values for the work function differences for one and two layer thin films are -1.1 and -1.4 eV, respectively, in good agreement with recent calculations and experiments.
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