Epitaxial growth of Bi(110) and Bi₂Se₃thin films on a ferromagnetic insulator substrate of Cr₂Ge₂Te₆

When a topological insulator (TI) is brought to the proximity of a ferromagnetic insulator (FMI), the breaking of the time-reversal symmetry may give rise to quantum anomalous Hall effect (QAHE). The physical properties of such TI-FMI systems are greatly affected by the interfacial structures of the components. Here, we report the growth and structural properties of Bi(110) and Bi₂Se₃thin films on a FMI of Cr₂Ge₂Te₆(CGT) substrate by scanning tunneling microscopy.We observed various defects and impurities on the CGT surfaces, which serve as the preferential sites for initial nucleation and epitaxial growth of Bi(110) thin films. The exposure of the as-grown Bi(110) thin films to Se vapor leads to the formation of polycrystalline Bi₂Se₃thin films with randomly distributed holes. The structure and composition of the as-prepared Bi₂Se₃thin films were further confirmed by Raman spectroscopy and x-ray photoelectron spectroscopy. Our work shows that the quality of the CGT crystals is vital for the growth of high-quality TIs on CGT substrates for QAHE 2021 IOP Publishing Ltd.