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

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 90 nm. 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.