Regensburg 2000 – scientific programme

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O: Oberflächenphysik

O 11: Postersession (Eröffnung)

O 11.50: Poster

Monday, March 27, 2000, 19:00–22:00, Bereich C

Structure and composition of O₂ exposed Cu thin films on Pt(111) — •R.-J. Linden, J.S. Tsay, T. Mangen, and K. Wandelt — Institut für Physikalische Chemie, Wegelerstr. 12, 53115 Bonn

Cu grows pseudomorphically on Pt(111) up to 1ML. Above 1.2ML additional LEED spots are observed. Dosing 12L O₂ at 330K destroys the order in a 1.2ML Cu film. Upon annealing to 625K a (2x2) structure is formed which is due to the presence of oxygen. This structure is stable up to 750K. Above 525K diffusion of Cu into Pt and alloying is observed for a 1ML Cu film using AES and UPS. The onset of diffusion is hardly influenced by oxygen. Alternate steps of depositing Cu and dosing O₂ followed by annealing to 450K after each gas dose yields a film of an estimated thickness of a few monolayers containing copper and oxygen. As monitored by sputter profiling the oxygen is distributed inhomogeneously in this film. Most of the oxygen is located both on the very surface and on the interface to Pt. Only a smaller amount of oxygen is found within the Cu layer, in agreement with the low solubility of oxygen in Cu.