Electrostatic effects and band bending in doped topological insulators.
Stanescu, Tudor D.
Date of Issue2012
School of Physical and Mathematical Sciences
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. Application of 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 ultrathin 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 state being localized within the same region in space.
DRNTU::Science::Physics::Electricity and magnetism
Physical review B
© 2012 American Physical Society. This paper was published in Physical Review B and is made available as an electronic reprint (preprint) with permission of American Physical Society. The paper can be found at the following official DOI: [10.1103/PhysRevB.86.195311]. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper is prohibited and is subject to penalties under law.