Synthesis and structural characterization of BiSbTe3 topological insulator single crystal

Abstract

We report the synthesis and structural characterization of the topological insulator BiSbTe3 single crystal. In Bi2Te3, the Fermi level (EF) lies in the bulk conduction band due to electron type bulk carriers induced by Te vacancies. While in Sb2Te3, Fermi level lies in the bulk valance band due to hole type bulk carriers induced by Sb-Te antisite defects. It is difficult to observe the topological properties by transport experiments due to excess contribution from bulk states. By mixing these two compounds, the ratio of bismuth (Bi) to antimony (Sb) can shift the Fermi level (EF) from bulk conduction band to bulk valance band providing an opportunity to realize ideal topological insulator with insulating bulk. In (Bi1-xSbx)2Te3, at Bi:Sb ratio of 1:1, the Fermi level lies in the bulk gap which is ideal for probing topological surface states through transport measurements. We have grown good quality single crystals of BiSbTe3 using modified Bridgman method. The X-ray diffraction analysis, Scanning electron microscopy and Energy dispersive electron spectroscopy confirms the single crystal formation, phase purity and stoichiometric atomic ratio of the prepared crystal. The electrical resistivity measurement of the crystal shows the metallic nature and high quality of the grown crystal.