The formation of CsAu films by successive evaporation of gold and caesium atoms onto a clean Ru(001) substrate surface was followed by UV photoelectron spectroscopy and (subsequent) thermal desorption spectroscopy. No compound but only a chemisorbed layer (and eventually bulk caesium) is formed if caesium is deposited onto a gold layer, if the quantity of the latter itself does not exceed the monolayer capacity. With thicker gold layers, on the contrary, semiconducting CsAu (with a band gap of 2.6 eV and the Fermi level close to the conduction band edge) is formed by interdiffusion at T > 250 K, but the outer surface consists always of a layer of chemisorbed caesium. This even holds for a “sandwich” system for which a thick gold film was evaporated onto a CsAu layer. The surface region of CsAu is highly reactive towards oxygen.
Preparation and characterization of thin CsAu films / M., Skottke Klein; A., Böttcher; R., Imbeck; S., Kennou; Morgante, Alberto; G., Ertl. - In: THIN SOLID FILMS. - ISSN 0040-6090. - STAMPA. - 203:(1991), pp. 131-145. [10.1016/0040-6090(91)90524-2]
Preparation and characterization of thin CsAu films
MORGANTE, ALBERTO;
1991-01-01
Abstract
The formation of CsAu films by successive evaporation of gold and caesium atoms onto a clean Ru(001) substrate surface was followed by UV photoelectron spectroscopy and (subsequent) thermal desorption spectroscopy. No compound but only a chemisorbed layer (and eventually bulk caesium) is formed if caesium is deposited onto a gold layer, if the quantity of the latter itself does not exceed the monolayer capacity. With thicker gold layers, on the contrary, semiconducting CsAu (with a band gap of 2.6 eV and the Fermi level close to the conduction band edge) is formed by interdiffusion at T > 250 K, but the outer surface consists always of a layer of chemisorbed caesium. This even holds for a “sandwich” system for which a thick gold film was evaporated onto a CsAu layer. The surface region of CsAu is highly reactive towards oxygen.Pubblicazioni consigliate
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