Topological insulator properties of Bi$_{2}$Se$_{3}$ thin films grown by HPCVD

Topological insulators (TIs) have a bulk band gap with conducting topological surface states (TSS) where conduction through these states is protected from impurity scattering by spin-momentum locking. Bi$_{2}$Se$_{3}$ thin films typically have a high n-type carrier concentration and show metallic behavior due to native defects such as Se vacancies. This makes it very difficult to directly observe the transport properties of the TSS in highly n-doped Bi$_{2}$Se$_{3}$ TI. We deposited Bi$_{2}$Se$_{3}$ thin films on (0001) Al$_{2}$O$_{3}$ by a hybrid physical chemical vapor deposition (HPCVD) technique which uses a high Se vapor pressure to reduce Se vacancies in the film. Magneto-transport measurements on these Bi$_{2}$Se$_{3}$ films showed metallic characteristics with n-type carriers and low carrier concentration. We clearly observed topological surface states in angle resolved photoemission spectroscopy (ARPES). The results of the characterization of these films by ARPES, XRD, XPS, AFM and magnetotransport are reported and discussed in the context of surface conductivity correlated with microstructure of Bi$_{2}$Se$_{3}$.