Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 34: Metal Substrates: Structure, Epitaxy and Growth

O 34.4: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Gold on Rhenium(10-10): A Combined STM and LEED Study — •Sebastian Schwede and Klaus Christmann — Inst. f. Chemie u. Biochemie FU Berlin

In complementing previous LEED and MEED experiments [1] we have performed an STM and LEED study on the growth of Au films on a Re(10-10) surface. While deposition at 300 K hardly leads to ordered growth, subsequent annealing to 850 K produces rectangular single-crystalline bilayer (BL) islands oriented parallel to the main crystal axes, with a size-dependent surface structure: islands with lengths between ca. 20 - 50 A exhibit a pseudomorphic (1x1) structure, while larger islands can no longer compensate the elastic strain caused by the lattice misfit and form (1xn) surface phases with n = 3, 4, 5. The Au diffusion seems to run via an intermediate precursor state located at and above the Au island edges. Films with Au coverages > 2 BL show a stable (1x8) structure that persists up to surprisingly high coverages of 30 BL. The STM images suggest a unique structural motif for all (1xn) phases that consists, in [0001] direction, of a bilayer line assembly with (n-1) Au bottom rows and (n-2) top rows, followed by an empty (vacant) row, a single Au row and another vacant row. In [1-210] direction the structure matches the Re - Re lattice spacing. [1] C. Pauls and K. Christmann J. Phys.: Condens. Matter 21 (2009) 134012