Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 17: Semiconductor Substrates
O 17.11: Vortrag
Montag, 31. März 2014, 18:30–18:45, PHY C 213
Epitaxial growth of the topological insulator Bi2Se3 on Si(111): Growth mode, lattice parameter, and strain state — •M. Vyshnepolsky1,2, C. Klein1, A. Hanisch-Blicharski1, and M. Horn-von Hoegen1 — 1Department of Physics, Universität Duisburg-Essen, Lotharstr. 1, D-47057 Duisburg, Germany — 2Present address: Lehrstuhl für Physikalische Chemie I, Ruhr-Universität Bochum, D-44780 Bochum, Germany
The epitaxial growth of Bi2Se3 films on Si(111), prepared by co- deposition of selenium (Se) and bismuth (Bi) at 200-250∘C, was studied by in-situ high resolution spot profile analysis low energy electron diffraction (SPA-LEED), ex-situ atomic force microscopy (AFM) and x-ray diffraction (XRD). The first Bi2Se3 layer grows as complete quintuple layer and covers the Si substrate before the next layer nucleates. Its lateral lattice parameter is increased by 1% compared with the value of a|| = 4.136 Å for a 6-nm-thick film. With increasing film thickness, a continuous change of the lattice parameter is observed to an asymptotic value of a||,∞ = 4.134 Å, which is explained by a van der Waals-like bonding between the Bi2Se3 film and the Si substrate [1]. The films are atomically smooth without small angle mosaics or small angle rotational domains. The precise determination of thus determined lateral and the vertical lattice parameter of c = 28.65 Å reveal that films grown at higher temperature exhibit smaller lattice parameters which is attributed to an increased density of Se vacancies. Bulk defects in the film cause a parabolic increase of the width of the diffraction peaks in XRD. [1] M. Vyshnepolsky et al., Appl. Phys. Lett. 103, 111909 (2013)