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Structural analysis of Co thin films grown on Ge(111) at room temperature by x‐ray photoelectron diffraction
Author(s) -
Tsuruta A.,
Chu W. G.,
Tamura K.,
Ishii H.,
Owari M.,
Nihei Y.
Publication year - 2005
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.1971
Subject(s) - orthorhombic crystal system , x ray photoelectron spectroscopy , diffraction , electron diffraction , low energy electron diffraction , crystallography , deposition (geology) , materials science , thin film , atmospheric temperature range , phase (matter) , cobalt , chemistry , metal , molecular beam epitaxy , epitaxy , layer (electronics) , crystal structure , nanotechnology , optics , nuclear magnetic resonance , metallurgy , physics , paleontology , organic chemistry , sediment , meteorology , biology
The thickness dependence of the structure of ultrathin Co films grown on Ge(111), using molecular beam epitaxy at room temperature, was studied via low energy‐electron diffraction (LEED) and x‐ray photoelectron diffraction. Cobalt deposition led to a surface phase transition from a c(2 × 8) reconstruction to a (1 × 1) structure. The (1 × 1) LEED pattern was gradually degraded with increased Co coverages, implying partial loss of long‐range order. Experimental and theoretical XPED studies revealed that 0.7 and 1.5 ML Co deposition resulted in the formation of a reacted surface layer mostly composed of a partly ordered orthorhombic CoGe 2 phase, whereas 5 and 10 ML deposition resulted not only in this surface phase but also in the formation of a partly ordered bcc Co metal on top. The formation mechanism of these structures in the ultrathin Co/Ge(111) films was elucidated in the light of the Effective Heat of Formation model and lattice mismatch. Copyright © 2005 John Wiley & Sons, Ltd.