OptimizingBi2−xSbxTe3−ySey

Abstract

To optimize the bulk-insulating behavior in the topological insulator materials having the tetradymite structure, we have synthesized and characterized single-crystal samples of Bi2−xSbxTe3−ySey (BSTS) solid solution at various compositions. We have elucidated that there are a series of "intrinsic" compositions where the acceptors and donors compensate each other and present a maximally bulk-insulating behavior. At such compositions, the resistivity can become as large as several Ωcm at low temperature and one can infer the role of the surface-transport channel in the non-linear Hall effect. In particular, the composition of Bi1.5Sb0.5Te1.7Se1.3 achieves the lowest bulk carrier density and appears to be best suited for surface transport studies.

Magneto-transport behaviour of Bi2Se3−xTex: role of disorder

“…Interestingly, the emergence of two carrier transports in figure 5 (b), correlates with the presence of transition from positive to negative magneto-resistance in figure 5 (a). Such non-linear behaviour has already been observed in similar TI samples and is reported to be due to the parallel contribution of both surface and bulk carrier to the transport [13,15,17,23].…”

“…Repeated experiments on randomly selected crystals showed similar behaviour providing support for the results presented in this paper. with a discernible saturation in resistivity below 30 K. Such a saturation tendency at low temperature has been reported to stem from the excess carriers from Se vacancies in the sample [15]. In the experiments by Ren et al [17] using different preparation procedure a weak upturn in resistivity at low temperature is reported.…”

Transport properties of topological insulators: Band bending, bulk metal-to-insulator transition, and weak anti-localization

“…[14,[18][19][20][21][22][23][24][25][26][27][28][29]. On the other hand, in the bulk limit shown in (g) at t = 1000 nm, Δ(t) is zero over most of the range of N BD and n SD .…”

Quantum oscillations of the topological surface states in low carrier concentration crystals of Bi2−xSbxTe3Pan1, Никитин2, Wu3 et al. 2016Solid State Communications7100View full textAdd to dashboardCite

“…In order to solve this problem several research directions have been pursued, among which charge carrier doping [11,12], thin film engineering and electrostatic gating [13,14]. Yet another route was promoted by Ren et al [15], namely to approach the intrinsic topological insulator regime by optimizing the Bi 2−x Sb x Te 3−y Se y (in short BSTS) composition. The composition around (x, y)=(0.50,1.3) was found to be the optimum for bulk insulating behavior, as evidenced by a resistivity of several Ωcm at liquid helium temperatures and a bulk carrier concentration of ∼ 2×10 16 cm −3 .…”