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arXiv · 1203.6411

Fermi level tuning and a large activation gap achieved in the topological insulator Bi_{2}Te_{2}Se by Sn doping

Zhi Ren·A. A. Taskin·Satoshi Sasaki·Kouji Segawa·Yoichi Ando
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Abstract

We report the effect of Sn doping on the transport properties of the topological insulator Bi_{2}Te_{2}Se studied in a series of Bi_{2-x}Sn_{x}Te_{2}Se crystals with 0 \leq x \leq 0.02. The undoped stoichiometric compound (x = 0) shows an n-type metallic behavior with its Fermi level pinned to the conduction band. In the doped compound, it is found that Sn acts as an acceptor and leads to a downshift of the Fermi level. For x \geq 0.004, the Fermi level is lowered into the bulk forbidden gap and the crystals present a resistivity considerably larger than 1 Ohmcm at low temperatures. In those crystals, the high-temperature transport properties are essentially governed by thermally-activated carriers whose activation energy is 95-125 meV, which probably signifies the formation of a Sn-related impurity band. In addition, the surface conductance directly obtained from the Shubnikov-de Haas oscillations indicates that a surface-dominated transport can be achieved in samples with several um thickness.

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Zhi Ren, A. A. Taskin, Satoshi Sasaki, Kouji Segawa, Yoichi Ando. 2012-03-29. Fermi level tuning and a large activation gap achieved in the topological insulator Bi_{2}Te_{2}Se by Sn doping. https://doi.org/10.1103/physrevb.85.155301

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