X-ray photoemission spectroscopy study of band bending at the interface of metal with poly(p-phenylene vinylene)

Autor: Yongli Gao, B. R. Hsieh, H. Razafitrimo, K. T. Park, E. Ettedgui
Rok vydání: 1995
Předmět:
Zdroj: Surface and Interface Analysis. 23:89-98
ISSN: 1096-9918
0142-2421
DOI: 10.1002/sia.740230208
Popis: We report on our recent x-ray photoemission spectroscopy investigations of the interface formation of metals with poly(p-phenylene vinylene) (PPV) prepared under various conditions. We have found that during deposition the metal reacts with residual hydroxyl groups in the polymer. In addition, we have found that Schottky barrier formation and the associated band bending depend strongly on surface preparation. In the case of Al deposition, samples converted in situ, containing 5% surface oxygen, show band bending that depends on the thickness of the metal overlayer, with effects arising after as little as 1 A of metal. On the other hand, a sample converted ex situ, with 10% surface oxygen, is insensitive to aluminium deposition. We feel that surface impurities and adsorbed species may delay Schottky barrier formation by acting as a butter layer that prevents the PPV substrate from interacting with the growing layer of Al. By constrast, the Ca/PPV surface surface exhibits delayed band bending, with strong interactions between surface oxygen and Ca. Our results indicate that band bending at the metal/PPV interface is governed by the metallicity of the metal overlaryer, which itself is influenced by the interface reaction of the deposited metal with the PPV substrate or the surface residual impurities. Finally, the degree of band bending observed did not correlate directly with the differences in work functions between the metals and PVV
Databáze: OpenAIRE
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