Structure of a Bi/Bi2Te3 heteroepitaxial film studied by x-ray crystal truncation rod scattering

We studied structure of a Bi(001)/Bi2Te3(001) heteroepitaxial film grown on Si(111) by means of surface x-ray diffraction. We revealed that on top of the Bi2Te3(001) film the similar to 7-bilayer-thick Bi(001) film is contracted in the surface plane by similar to 3% and is expanded along the vertical direction by similar to 4% compared with the bulk values. The epitaxial strain supports the realization of the topological phase transition of the Bi film [Hirahara et al., Phys. Rev. Lett. 109, 227401 (2012)]. We also revealed structural properties of the Bi2Te3(001)/Si(111) interface. The electron density profile in the vertical direction, obtained by the combination of the holographic method and phase retrieval methods, exhibits a wetting layer at the interface. It is also indicated that the bottom two Bi2Te3 layers act as a buffer layer for further growth of the crystalline film. DOI: 10.1103/PhysRevB.87.075449