Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi2Te2Se

Abstract

A comparative study of the properties of topological insulator Bi2Te2Se (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 x 1014 cm-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 (EF) for the Sn-doped crystals falls cleanly in the surface states with no interference from the bulk bands, that 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 of Energy near EF. 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.

arXiv comment24 pages, 7 figures

References in corpus (15)

• Topological Insulators in Three Dimensions
• Discovery (theoretical prediction and experimental observation) of a large-gap topological-insulator class with spin-polarized single-Dirac-cone on the surface
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological invariants of time-reversal-invariant band structures
• Large bulk resistivity and surface quantum oscillations in the topological insulator Bi2Te2Se
• Observation of topological order in a Superconducting doped topological insulator (based on the Bi2Se3 class)
• Observation of Dirac Holes and Electrons in a Topological Insulator
• Optimizing the Bi_(2-x)Sb_(x)Te_(3-y)Se_(y) solid solutions to approach the intrinsic topological insulator regime
• Electronic Structure of the Topological Insulator Bi2Se3 Using Angle-Resolved Photoemission Spectroscopy: Evidence for a Nearly Full Surface Spin Polarization
• Photoemission Spectroscopy of Magnetic and Non-magnetic Impurities on the Surface of the Bi${}_2$Se${}_3$ Topological Insulator
• High-Field Shubnikov-de Haas Oscillations in the Topological Insulator Bi${}_2$Te${}_2$Se
• Quantum Oscillations in a Topological Insulator Bi${}_2$Te${}_2$Se with Large Bulk Resistivity (6 $\Omega$cm)
• Low carrier concentration crystals of the topological insulator Bi${}_2$Te${}_2$Se
• Fermi level tuning and a large activation gap achieved in the topological insulator Bi_{2}Te_{2}Se by Sn doping
• Why is the bulk resistivity of topological insulators so small?

Cited by in corpus (10)

• Sn-doped Bi1.1Sb0.9Te2S, a bulk topological insulator with ideal properties
• Resonant levels, vacancies and doping in Bi2Te3, Bi2Te2Se and Bi2Se3 tetradymites
• Resonance-state-induced superconductivity at high Indium contents in In-doped SnTe
• Revealing puddles of electrons and holes in compensated topological insulators
• The role of surface chemical reactivity in the stability of electronic nanodevices based on two-dimensional materials "beyond graphene" and topological insulators
• Electronic properties of Bi${}_2$Se${}_3$ dopped by $3d$ transition metal (Mn, Fe, Co, or Ni) ions
• Universal scaling for the spin-electricity conversion on surface states of topological insulators
• MOCVD synthesis of compositionally tuned topological insulator nanowires
• Universal superconductivity phase diagram for pressurized tetradymite topological insulators
• High and Magnetic-field-dependent Surface Carriers Mobility in 3D Topological Insulators without Bulk States