Improvement of Electrical Transport Performance of BiSbTeSe by Elemental Doping.

A topological insulator with large bulk-insulating behavior and high electron mobility of the surface state is needed urgently, not only because it would be a good platform for studying topological surface states but also because it is a prerequisite for potential future applications. In this work, we demonstrated that tin (Sn) or indium (In) dopants could be introduced into a BiSbTeSe single crystal. The impacts of the dopants on the bulk-insulating property and electron mobility of the surface state were systematically investigated by electrical transport measurements. The doped single crystals had the same crystal structure as the pristine BiSbTeSe, no impure phase was observed, and all elements were distributed homogeneously. The electrical transport measurements illustrated that slight Sn doping could improve the performance of BiSbTeSe a lot, as the longitudinal resistivity (), bulk carrier density (), and electron mobility of the surface state () reached about 11 Ωcm, 7.40 × 10 cm, and 6930 cm/(Vs), respectively. By comparison, indium doping could also improve the performance of BiSbTeSe with , , and up to about 13 Ωcm, 1.29 × 10 cm, and 4500 cm/(Vs), respectively. Our findings suggest that Sn- or indium-doped BiSbTeSe crystals should be good platforms for studying novel topological properties, as well as promising candidates for low-dissipation electron transport, spin electronics, and quantum computing.