Growth of Bi2Se3 topological insulator thin film on Ge(111) substrate

Atomically smooth, single crystalline Bi2Se3 thin films were grown on a Ge(111) substrate using molecular beam epitaxy. Crystallinities of both the surface and the bulk as well as the stoichiometry of the grown film were characterized by using low-energy electron diffraction, scanning tunneling microscopy, X-ray diffraction, and photoelectron spectroscopies. Hexagonal atomic structures, quintuple layer steps observed in STM images confirmed that the Bi2Se3 film with a (0001) surface was grown. Diffraction peak positions as well as the chemical composition determined from the core-level photoelectron spectra coincide well with those expected for the Bi2Se3 crystal. The surface state with a Dirac cone was observed in the valence photoelectron spectra, which also support that a high-quality Bi(2)Se3 film was grown on the Ge(111) substrate. The interface between Ge(111) and Bi2Se3(0001) is expected to be abrupt due to the small lattice between them. (C) 2017 Elsevier B.V. All rights reserved.