Electrostatic effects and band-bending in doped topological insulators

Abstract

We investigate the electrostatic effects in doped topological insulators by developing a self consistent scheme for an interacting tight binding model. The presence of bulk carriers, in addition to surface electrons, generates an intrinsic inhomogeneous charge density in the vicinity of the surface and, as a result, band bending effects are present. We find that electron doping and hole doping produce band bending effects of similar magnitude and opposite signs. The presence of additional surface dopants breaks this approximate electron-hole symmetry and dramatically affects the magnitude of the band bending. Applying a gate potential can generate a depletion zone characterized by a vanishing carrier density. We find that the density profile in the transition zone between the depleted region and the bulk is independent of the applied potential. In thin films the electrostatic effects are strongly dependent on the carrier charge density. In addition, we find that substrate induced potentials can generate a Rashba type spin-orbit coupling in ultra thin topological insulator films. We calculate the profiles of bulk and surface states in topological insulator films and identify the conditions corresponding to both types of states being localized within the same region in space.

9 pages, 10 figures

References in corpus (10)

• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• 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 Field Theory of Time-Reversal Invariant Insulators
• Gate-Voltage Control of Chemical Potential and Weak Anti-localization in Bismuth Selenide
• Bulk Fermi surface coexistence with Dirac surface state in Bi${}_2$Se${}_3$: a comparison of photoemission and Shubnikov-de Haas measurements
• On the $Z_2$ classification of Quantum Spin Hall Models
• Exciton condensation and charge fractionalization in a topological insulator film
• Nonlinear optical probe of tunable surface electrons on a topological insulator

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• Signature of a topological phase transition in the Josephson supercurrent through a topological insulator
• Photocurrents in Bi2Se3: bulk versus surface, and injection versus shift currents
• Dirac cone shift of a passivated topological Bi2Se3 interface state
• Robustness of Topological Superconductivity in Proximity-Coupled Topological Insulator Nanoribbons
• Band bending at the surface of Bi${}_2$Se${}_3$ studied from first principles
• Tuning Dirac nodes with correlated d-electrons in BaCo_{1-x}Ni_{x}S_{2}
• Intrinsic surface dipole in topological insulators