Growth And Characterization Of Two-dimensional Layered Bi₂Te_3-xSe_x And Bi₂Te（3-x）Se_x/Graphene Heterostructrue

Recently, two-dimensional(2D) toplogical insulators(TIs) attact great attention in the fields of condensed matter physics and materials. In comparison to three-dimensional(3D) TIs, 2D TIs can effectively highlight the contribution of electronic state on the surface, affording these materials wide applications for quantum computing, spin devices as well as micro-nano photoelectric devices. Although there are many synthesis methods to produce 2D Bi2Te3-xSex platelets and Bi2Te3-xSex/graphene, there is still a lot space to optimise the growth conditons. Using the chemical growth methods, the aim of this thesis is to study the controllable synthesis of 2D Bi2Te3-xSex plateletes and Bi2Te3-xSex/graphene. These contents of this thesis are summarized as following.1. We develop a facile solvothermal method to produce both binary and ternary compounds of bismuth chalcogenides in the form of Bi2Te3-xSex, and graphene/Bi2Te3-xSex. We systematically investigated the relationship between microstructure and phonon scattering by Raman spectroscopy at four different excitation wavelengths. The size and morphology of crystal play an important on the Raman vibrational modes.2. We investigate a vapor phase deposition method to grow Bi2Se3 and Bi2Te3 on various substrates(Si, Si O2, mica, etc). By controlling the growth conditions and choosing suitable substrates, we obtained platelets and film of Bi2Se3 and Bi2Te3 crystals. The thickness of TI crystals is less than 20 nm and the size of the platelets is lager than 10 μm.3. We present a vapor phase deposition method for in-situ growth of Bi2Te3-xSex, x=(0 1 2 3) on graphene. After transferring graphene to Si O2 substrates, we obtained high quality Bi2Te3-xSex/graphene heterostructure materials on Si O2 substrates.