Strain state, film and surface morphology of epitaxial topological insulator Bi2Se3 films on Si(111)

Abstract

Epitaxial Bi2Se3 films were grown by molecular beam epitaxy on Si(111)-Bi(3×3)R30° at temperatures between 200 and 250°C. The surface and bulk morphology was characterized by high resolution low energy electron diffraction, X-ray diffraction, and atomic force microscopy for various film thicknesses between 6 and 90nm. The films are atomically smooth without small angle mosaics or small angle rotational domains. The precise determination of lattice parameter reveals that films grown at higher temperature exhibit a smaller value for the vertical lattice parameter. The presence of random stacking faults in the film is reflected by a parabolic increase of the width of the diffraction peaks in X-ray diffraction.