Observation of nano-scaled defects in Fe doped Bi2Se3 topological insulator crystal

Magnetic atom doped topological insulator (FexBi2−xSe3) crystals were prepared though melt-grown reaction. The lattice parameter c of doped samples was lower than that of undoped sample. The carrier density decreased monotonically with increasing Fe content. Three types of nano-scaled Fe enriched defects were detected. Defects were effectively suppressed after annealing treatment and Fe atoms became homogeneous in crystals. The carrier density of samples with annealing treatment was about one order of magnitude lower than that of non-annealed samples, which implied that annealing treatment facilitated Fe3+ substituting Bi3+ and suppressing Se vacancies. Our study paved the way for making high quality of topological insulator single crystals.

► Nano-scaled defects were detected in Fe doped in Bi2Se3 single crystals.
► Defects were effectively suppressed after annealing treatment.
► The carrier density of annealed samples is lower that of non-annealed samples.