Epitaxial growth of Cu on Ag(111) studied with angle-resolved photoemission spectroscopy

• Published in: Applied surface science 2015-11, Vol.354, p.235-239
• Main Authors: Luh, Dah-An, Huang, Chih-Hao, Cheng, Cheng-Maw, Tsuei, Ku-Ding
• Format: Article
• Language: English
• Subjects: ARPES; Epitaxial growth; Metallic thin films; Surface state
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2014.12.123

•The growth of Cu on Ag(111) is studied with ARPES and LEED.•The morphology of Cu/Ag(111) is determined on analyzing its surface states.•Annealed Cu films on Ag(111) are covered with Ag showing a (9×9) reconstruction.•Defects existing in the Cu film penetrate deeply into the Ag(111) substrate.•Ag atoms migrate to the Cu surface along the wall of the holes in the Cu film. The growth of Cu on Ag(111) under varied growth conditions was investigated with angle-resolved photoemission spectra. The evolution of Cu/Ag(111) during annealing was characterized on monitoring its surface states. The surface morphology of a Cu film on Ag(111) depends on the temperature and the Cu coverage. Islands or crystalline films develop when Cu is deposited at ∼300K. Defects in the Cu films penetrate deeply into the Ag(111) substrate and expose the Ag(111) surface. The deposition of Cu at a low temperature results in disordered films. On annealing, the films become ordered with defects. Our results show the segregation of Ag on the Cu surface, which occurs at 300K and becomes accelerated significantly at ∼380K. After being annealed above 430K, all islands and films of Cu are fully covered with Ag, showing a (9×9) reconstruction. Our results indicate also that the segregation of Ag on the Cu surface occurs only after the Ag(111) surface is exposed, indicating that Ag atoms migrate to the Cu(111) surface, not through bulk Cu, but along the walls of the islands and the defects in the films.