Kelvin probe and scanning tunneling microscope characterization of Langmuir–Blodgett sapphyrin films

The work function of solid layers of increasing thicknesses of E2M8− sapphyrin, deposited on a gold substrate by the Langmuir–Blodgett method, has been measured by the Kelvin-probe technique. The results show that the contact-potential-difference values depend upon the layer thickness, reaching satu...

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Bibliographic Details
Published in:Applied physics letters 1999-08, Vol.75 (9), p.1237-1239
Main Authors: Goletti, C., Sgarlata, A., Motta, N., Chiaradia, P., Paolesse, R., Angelaccio, A., Drago, M., Di Natale, C., D’Amico, A., Cocco, M., Troitsky, V. I.
Format: Article
Language:English
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Summary:The work function of solid layers of increasing thicknesses of E2M8− sapphyrin, deposited on a gold substrate by the Langmuir–Blodgett method, has been measured by the Kelvin-probe technique. The results show that the contact-potential-difference values depend upon the layer thickness, reaching saturation after a certain amount of deposited sapphyrin. Scanning tunneling microscope images taken at the same coverages show that corresponding with this threshold, sapphyrin forms a true continuous layer on gold, completely covering the substrate. Evolution of the layer towards its completion is accompanied by a continuous variation of the work-function value, consistent with an increasing dipole term due to the interaction of sapphyrin with the metal substrate.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.124653