Revealing puddles of electrons and holes in compensated topological insulators

Abstract

Three-dimensional topological insulators harbour metallic surface states with exotic properties. In transport or optics, these properties are typically masked by defect-induced bulk carriers. Compensation of donors and acceptors reduces the carrier density, but the bulk resistivity remains disappointingly small. We show that measurements of the optical conductivity in BiSbTeSe${}_2$ pinpoint the presence of electron-hole puddles in the bulk at low temperatures, which is essential for understanding DC bulk transport. The puddles arise from large fluctuations of the Coulomb potential of donors and acceptors, even in the case of full compensation. Surprisingly, the number of carriers appearing within puddles drops rapidly with increasing temperature and almost vanishes around 40 K. Monte Carlo simulations show that a highly non-linear screening effect arising from thermally activated carriers destroys the puddles at a temperature scale set by the Coulomb interaction between neighbouring dopants, explaining the experimental observation semi-quantitatively. This mechanism remains valid if donors and acceptors do not compensate perfectly.

11 pages with 7 figures plus supplemental material (3 pages)

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Cited by in corpus (39)

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• Enhanced electron dephasing in three-dimensional topological insulators
• Quantum confinement of the Dirac surface states in topological-insulator nanowires
• Phonon mode calculations and Raman spectroscopy of the bulk-insulating topological insulator BiSbTeSe${}_2$
• Majorana bound states in topological insulators without a vortex
• Current-induced breakdown of the quantum anomalous Hall effect
• Opto-Electronic Characterization of Three Dimensional Topological Insulators
• Single full gap with mixed type-I and type-II superconductivity on surface of the type-II Dirac semimetal PdTe2 by point-contact spectroscopy
• Conductivity of two-dimensional narrow gap semiconductors subjected to strong Coulomb disorder
• Mixed type I and type II superconductivity due to intrinsic electronic inhomogeneities in the type II Dirac semimetal PdTe2
• Interaction between counter-propagating quantum Hall edge channels in the 3D topological insulator BiSbTeSe${}_2$
• Hyers-Ulam stability of elliptic Möbius difference equation
• Length scale of puddle formation in compensation-doped semiconductors and topological insulators
• Metallization and proximity superconductivity in topological insulator nanowires
• Charge puddles in a completely compensated topological insulator
• Two-Level Systems in Nucleated and Non-Nucleated Epitaxial alpha-Tantalum films
• 2D-Dirac surface states and bulk gap probed via quantum capacitance in a 3D topological insulator
• Spatially varying electronic dephasing in three dimensional topological insulators
• Disorder effects in topological insulator nanowires
• Size Constraints on Majorana Beamsplitter Interferometer: Majorana Coupling and Surface-Bulk Scattering
• Phonon thermal Hall effect in charge-compensated topological insulators
• Absence of strong localization at low conductivity in the topological surface state of low disorder Sb2Te3
• Nonlinear transport due to magnetic-field-induced flat bands in the nodal-line semimetal ZrTe5
• Enhancement of hopping conductivity by spontaneous fractal ordering of low-energy sites
• Electronic excitations in $5d^4$ J=0 Os${}^{4+}$ halides studied by RIXS and optical spectroscopy
• Transport properties of band engineered p-n heterostructures of epitaxial Bi${}_2$Se${}_3$/(Bi${}_{1-x}$Sb${}_x$)${}_2$(Te${}_{1-y}$Se${}_y$)${}_3$ topological insulators
• Conductivity of two-dimensional small gap semiconductors and topological insulators in strong Coulomb disorder
• Large positive magneto-conductivity at microwave frequencies in the compensated topological insulator BiSbTeSe2
• Relaxation dynamics of the optically driven nonequilibrium states in the electron- and hole-doped topological-insulator materials $(B{i}_{1-x}S{b}_x{)}_{2}T{e}_3$
• Strong and Weak Three-Dimensional Topological Insulators Probed by Surface Science Methods
• Reversible Engineering of Topological Insulator Surface State Conductivity through Optical Excitation
• Quantum theory of the magnetochiral anisotropy coefficient in ZrTe${}_5$
• Switching on surface conduction in a topological insulator
• Selective-Area Epitaxy of Bulk-Insulating (Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_3$ Films and Nanowires by Molecular Beam Epitaxy
• Quasiparticle interference on the surface of Bi${}_2$Se${}_3$ terminated (PbSe)${}_5$(Bi${}_2$Se${}_3$)${}_6$
• Plasmons in semiconductor and topological insulator wires with large dielectric constant