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Title: Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi{sub 2}Te{sub 2}Se

A comparative study of the properties of topological insulator Bi{sub 2}Te{sub 2}Se (BTS) crystals grown by the vertical Bridgeman method is described. Two defect mechanisms that create acceptor impurities to compensate for the native n-type carriers are compared: Bi excess, and light Sn doping. Both methods yield low carrier concentrations and an n-p crossover over the length of the grown crystal boules, but lower carrier concentrations and higher resistivities are obtained for the Sn-doped crystals, which reach carrier concentrations as low as 8 × 10{sup 14} cm{sup −3}. Further, the temperature dependent resistivities for the Sn-doped crystals display strongly activated behavior at high temperatures, with a characteristic energy of half the bulk band gap. The (001) cleaved Sn-doped BTS crystals display high quality Shubnikov de Haas (SdH) quantum oscillations due to the topological surface state electrons. Angle resolved photoelectron spectroscopy (ARPES) characterization shows that the Fermi energy (E{sub F}) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, which the Dirac point for the surface states lies approximately 60 meV below the top of the bulk valence band maximum, and allows for a determination of the bulk and surface state carrier concentrations as a function ofmore » Energy near E{sub F}. Electronic structure calculations that compare Bi excess and Sn dopants in BTS demonstrate that Sn acts as a special impurity, with a localized impurity band that acts as a charge buffer occurring inside the bulk band gap. We propose that the special resonant level character of Sn in BTS gives rise to the exceptionally low carrier concentrations and activated resistivities observed.« less
Authors:
; ;  [1] ; ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6]
  1. Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)
  2. Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)
  3. (United States)
  4. National Synchrotron Light Source, Brookhaven National Lab, Upton, New York 11973 (United States)
  5. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)
  6. Condensed Matter Physics and Materials Science Department, Brookhaven National Lab, Upton, New York 11973 (United States)
Publication Date:
OSTI Identifier:
22273594
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 14; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; BISMUTH SELENIDES; BISMUTH TELLURIDES; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; CRYSTAL DEFECTS; CRYSTALS; DOPED MATERIALS; ELECTRONIC STRUCTURE; ELECTRONS; OSCILLATIONS; PHOTOELECTRON SPECTROSCOPY; SURFACES; TEMPERATURE DEPENDENCE; TOPOLOGY; VALENCE